Paying off a mortgage?

[Dominic Punzo]

This question isn't actually for me. It's for my parents but if I can manage to help them out than it'll be of great help to me. So recently my parents came into some money. It's nothing crazy or life changing but it would be enough of a sum to pay down a really good portion of their mortgage. My questions is should they do this and if they do will there be any benefits or penalties to their mortgage and or monthly payment?