Ive been friends with a girl for about 5 years and I believe she needs to get away from her father and stepmother. Since I have known her her stepmother has not worked a single day and her father is unable to work due to medical reasons and is still waiting for disability. She is 17 and is going to school 5 days a week and working 6 days a week.
On her payday the only time she touches her check is when she signs it then her parents take it to the bank and she never sees a dime of her own money.
When she gets home from going to school and working she has to clean the house and take care of and watch her two younger sisters while her parents sit in their bedroom with the door shut watching TV.
If she actually has free time her parents won't allow her to go anywhere, do anything, or have friends over.
She's a great person and it kills me to see her have all of the parents responsibilities placed on her. What should she do?

I don't see any abuse here. It sounds like she's pitching in to help her family. You can always call Child Welfare (or whatever it's called in your area) and report the situation but, again, I don't see abuse.

When she is 18, self supporting, with a place to live of her own she can leave the situation.

In the meantime, has she talked to a school counsellor, clergyperson, relative about the situation?

I don't understand the won't allow her to go anywhere, do anything, have friends over part. She is not allowed to leave the house except for work and school?