I'm sorry you're going through this. I know how much it hurts to be at odds with a daughter. However, your daughter is 19 years old and as such, is considered an adult. If she wants to stay with your parents, and they want her there, then why not just let it be? Maybe just step back from the whole situation for a while?
Things have a way of working out one way or the other, but with continual pushing and shoving from both sides, it just keeps everything in upheaval. Maybe just accept that things are what they are at this point. Give it some time and let things settle for a bit?