Any further question? What best to ask on one's last chance?

• I think the canonical answer to that question was silence.

  Then the Buddha said to the mendicants:

  “Perhaps even a single mendicant has doubt or uncertainty regarding the Buddha, the teaching, the Saṅgha, the path, or the practice. So ask, mendicants! Don’t regret it later, thinking: ‘We were in the Teacher’s presence and we weren’t able to ask the Buddha a question.’” When this was said, the mendicants kept silent. 6.6For a second time, and a third time the Buddha addressed the mendicants:

  “Perhaps even a single mendicant has doubt or uncertainty regarding the Buddha, the teaching, the Saṅgha, the path, or the practice. So ask, mendicants! Don’t regret it later, thinking: ‘We were in the Teacher’s presence and we weren’t able to ask the Buddha a question.’” For a third time, the mendicants kept silent. Then the Buddha said to the mendicants:

  “Mendicants, perhaps you don’t ask out of respect for the Teacher. So let a friend tell a friend.” When this was said, the mendicants kept silent. Then Venerable Ānanda said to the Buddha:

  “It’s incredible, sir, it’s amazing! I am quite confident that there’s not even a single mendicant in this Saṅgha who has doubt or uncertainty regarding the Buddha, the teaching, the Saṅgha, the path, or the practice.” “Ānanda, you speak from faith. But the Realized One knows that there’s not even a single mendicant in this Saṅgha who has doubt or uncertainty regarding the Buddha, the teaching, the Saṅgha, the path, or the practice. Even the last of these five hundred mendicants is a stream-enterer, not liable to be reborn in the underworld, bound for awakening.”

  Then the Buddha said to the mendicants:

  “Come now, mendicants, I say to you all: ‘Conditions fall apart. Persist with diligence.’” These were the Realized One’s last words.

• I once thought to ask:

  What advice would you give, what's your best answer, if you weren't constrained by the question-and-answer format of this site? What question would you like to be asked, what question should I ask, and your answer to that question?

  Perhaps that's not a good fit though, a normal type of question, for this site. It might be good to post in chat if you were inclined to.

• It might be useful to ask, "How best to talk to someone who is dying"?

  The only (little) advice I have read on that subject is here (from page 82 of Ven. Thanissaro's commentary on The Buddhist Monastic Code):

  Thus, the Commentary notes, a bhikkhu talking to a dying patient should [... focus on ...] how to inspire the patient with the following thoughts:

  “The attainment of the paths and fruitions is not out of the ordinary for a virtuous person. So, having formed no attachment for such things as your dwelling, and establishing mindfulness in the Buddha, Dhamma, Sangha, or the body, you should be heedful in your attention.”

  The Vinita-vatthu to Pr 4 contains a number of stories in which bhikkhus comfort a dying bhikkhu by asking him to reflect on what he has attained through the practice, which was apparently a common way of encouraging a dying bhikkhu to focus his thoughts on the best object possible. The suttas also contain advice on how to encourage patients facing death. See, for example, MN 143, SN 36.7, and AN 6.16. In all of these cases, the advice is aimed [...] at inspiring calm and insight.

  If the answer could explain how to talk to monks, Buddhist lay-people, and non-Buddhist lay-people, that would be ideal.

  Non-Buddhist lay-people especially, perhaps friends and family members, because I meet more of them than I meet Buddhists, and I'm not sure how to translate that quote ...

  comfort a dying bhikkhu by asking him to reflect on what he has attained through the practice, which was apparently a common way of encouraging a dying bhikkhu to focus his thoughts on the best object possible

  ... into non-Buddhist terminology.

  I last asked a similar question: How do you talk to someone whose loved one is dying?

You have the one final chance to ask one thing. What would it be?

That was Bahiya's problem in Udana 1.10 (quoted below). Bahiya, the advanced ascetic who was not enlightened, sought to understand in a short teaching the gist of the Dhamma that would free him.

This question would be like "What would be the shortest summary of the Buddha's teachings that is enough to liberate me from suffering?"

Then Bāhiya, hurriedly leaving Jeta's Grove and entering Sāvatthī, saw the Blessed One going for alms in Sāvatthī — serene & inspiring serene confidence, calming, his senses at peace, his mind at peace, having attained the utmost tranquility & poise, tamed, guarded, his senses restrained, a Great One (nāga). Seeing him, he approached the Blessed One and, on reaching him, threw himself down, with his head at the Blessed One's feet, and said, "Teach me the Dhamma, O Blessed One! Teach me the Dhamma, O One-Well-Gone, that will be for my long-term welfare & bliss."

When this was said, the Blessed One said to him, "This is not the time, Bāhiya. We have entered the town for alms."

A second time, Bāhiya said to the Blessed One, "But it is hard to know for sure what dangers there may be for the Blessed One's life, or what dangers there may be for mine. Teach me the Dhamma, O Blessed One! Teach me the Dhamma, O One-Well-Gone, that will be for my long-term welfare & bliss."

A second time, the Blessed One said to him, "This is not the time, Bāhiya. We have entered the town for alms."

A third time, Bāhiya said to the Blessed One, "But it is hard to know for sure what dangers there may be for the Blessed One's life, or what dangers there may be for mine. Teach me the Dhamma, O Blessed One! Teach me the Dhamma, O One-Well-Gone, that will be for my long-term welfare & bliss."

"Then, Bāhiya, you should train yourself thus: In reference to the seen, there will be only the seen. In reference to the heard, only the heard. In reference to the sensed, only the sensed. In reference to the cognized, only the cognized. That is how you should train yourself. When for you there will be only the seen in reference to the seen, only the heard in reference to the heard, only the sensed in reference to the sensed, only the cognized in reference to the cognized, then, Bāhiya, there is no you in connection with that. When there is no you in connection with that, there is no you there. When there is no you there, you are neither here nor yonder nor between the two. This, just this, is the end of stress."

Through hearing this brief explanation of the Dhamma from the Blessed One, the mind of Bāhiya of the Bark-cloth right then and there was released from effluents through lack of clinging/sustenance. Having exhorted Bāhiya of the Bark-cloth with this brief explanation of the Dhamma, the Blessed One left.

Now, not long after the Blessed One's departure, Bāhiya was attacked & killed by a cow with a young calf. Then the Blessed One, having gone for alms in Sāvatthī, after the meal, returning from his alms round with a large number of monks, saw that Bāhiya had died. On seeing him, he said to the monks, "Take Bāhiya's body, monks, and, placing it on a litter and carrying it away, cremate it and build him a memorial. Your companion in the holy life has died."

Responding, "As you say, lord," to the Blessed One, the monks — placing Bāhiya's body on a litter, carrying it away, cremating it, and building him a memorial — went to the Blessed One. On arrival, having bowed down to him, sat to one side. As they were sitting there, they said to him, "Bāhiya's body has been cremated, lord, and his memorial has been built. What is his destination? What is his future state?"

"Monks, Bāhiya of the Bark-cloth was wise. He practiced the Dhamma in accordance with the Dhamma and did not pester me with issues related to the Dhamma. Bāhiya of the Bark-cloth, monks, is totally unbound."