Hospital not abiding by contract.

Posting for a friend, she just moved out to California from Minnesota to do a 13 week Traveling Ultrasound position. In her contract it says her hours would be 7am-3pm M-F with no weekends and she showed up and they said they need her to work 3pm-11pm M-F and rotating weekends. How would you go about this situation. She is so stressed out and doesn’t know what to do.