I can understand why her parents would welcome her home. They love her.
I do pray they will be on their guard, though. The daughter did not like living with the punishment that was instated after a series of disobedience (drinking, skipping school, attending a school dance while drunk), and so took off. She didn't want to give up her phone and other privileges, nor did she want to break up with her boyfriend.
She moved in with one of her best friends, whose father paid for the lawsuit. The daughter is smart, and might have returned home thinking she can gain the upper hand again. The parents are going to have to remain strong and to stick to their principals. The skeptic in me wouldn't trust her as far as I could see her.
It's quite possible, however, that after the humiliation of being in court, the daughter has truly repented her rebellion and hate-filled messages to her parents (particularly her Mom), and has returned home with nothing but love in her heart.