What should a girl do if family threatens after marriage?

Sir, there is a girl who got married in Arya Samaj Temple with her free consent, but no one knows about it. She has the marriage certificate and is of legal age. However, her family doesn’t know, and they want her to marry someone else. When she refuses, they threaten to kill her and have physically assaulted her multiple times. She is currently staying at her home due to exams but plans to go with her husband afterward. Her phone has been taken, and they are threatening her life. What should she do? Please advise.