Let’s suppose if I have done masah on my right foot, and when I’m about to do masah on my left foot, water drops fall on my left foot. In this situation, should I wipe my feet first, and then do masah, or do the wuzu all over again?

While doing Masah if water fall down then continue your masah at the same time wipe it with other hand and you don’t need to repeat the wudhu.