If I take in my elderly parent is it legitimate to ask for some compensation?

Consider. Did your parent(s) ask for compensation from you during the years you lived with them & were reared by them? Are there other siblings who might contribute to his/her care? Council on aging may be able to offer suggestions.
Clarify please. It is a parent who fed,diapered and clothed you for years.It is a parent that made sure you had lunch money, got to practice, did your homework so you wouldn't fail, but you want to be paid for assisting them.Is this what you are asking ? Or are you a certified attendant working for someone else. In the later case I can see it.In the former case you sound quite shallow.