Jerry Martin (jerrynsteph4eva) plays Mario Is Missing! (Super Nintendo) - Part 8 of 8

Here's your ending.

Almost all questions and answers come courtesy of DEngel's GameFAQs NES walkthrough, since the game's questions come from it.

Roy

Just jump on his head six times.

You did it. Now make your way to the top floor and you'll get the ending, where Bowser gets launched into Antarctica and is forced to freeze to death.