Upvote:1
You will need a multiple entry visa for Malaysia, as each time you enter or re-enter Malaysia counts as a new entry irregardless of how long you visit for or how long you leave the country for.
Visa details: http://www.kln.gov.my/web/npl_kathmandu/requirement_foreigner
You need a visa to visit Thailand as well, which needs to be obtained in advance. Nepali citizens do not qualify for VOA like Indian citizens.
Is there a reason (other than collecting passport stamps) for your one day visit to Thailand? Seems like a lot of visa expense and headaches for a whirlwind visit.