If she has to pay the legal fees because of work she is doing on your son's behalf, then yes. That would include fees she has to pay because you are opposing her guardianship, just in case that's why you ask.
If the fees arise from something completely different that has absolutely nothing to do with your son, at all, then no.
If the fees arise from something completely different that has absolutely nothing to do with your son, at all, then no.