This is a family matter that I think is best worked out privately before running to the authorities. That could leave scars that won't ever heal. Perhaps this young woman could find a third party to act as a mediator between herself and her parents. They could meet in a neutral place with this person and discuss what needs done to make them all comfortable.

Quite honestly this is a 20 year old adult. It sounds like she needs to leave the nest and establish her own home where she can make her own rules. If she can afford a car, credit cards and so forth there's no reason she shouldn't be able to manage a nice, small apartment of her own. There seems a really strange thing going on with this generation that they want to stay home with mommy and daddy but still want to be an independent adult. That just generally never works out very well.