Yes moth balls do keep skunks away as they put out a bad odor that skunks hate.
Skunks will avoid any areas that you put out moth balls around.
You can also place ammonia soaked cotton balls in areas where skunks hang around to keep them away too.
Just make sure that kids or dogs or cats etc cannot get into the moth balls or ammonia soaked cotton balls.
Skunks also hate the smell of Citrus which will keep the skunks away but if you can do so you should shoot the skunk to keep the skunk from coming back.
You do not want to get sprayed by a skunk or have your child or pets sprayed by a skunk because the smell is awful and hard to get rid of.