score:3
Within your own question, you've already composed an excellent response, and @GayotFow and @phoog have shared their expert guidance in their comments.
The plan is that you, your mother and brother will book the same flight to Germany; you'll take up residence and work, they'll go home in several weeks.
In your visa application, respond 'yes,' you would be accompanied, that your mother and brother plan to travel with you to help you settle in. Add an explanatory note, that they are applying, separately, for the Schengen Short Stay visa, describe their planned itinerary. Discuss it during your interview.
Your family members should answer 'yes' to the same, or similar, questions in their visa applications, explain the circumstances, and discuss during their interview.
Whatever the term: accompany, travel, go with; fully describe your intentions and plans.