Children in possible danger

I am seeking advice for my friend who lives in north Carolina with his wife and his 4 children 2 of which are also his wife’s. He is in the process of making plans to leave her due to long term emotional strain on him and their home. In the last three years he has had to commit his wife to a mental institution and to a drug rehab twice. She has tried to commit suicide twice that I am aware of, also. My friend has done his very best to shelter his children from the outbursts and all out “craziness” his wife has displayed over these years but it is getting more and more hard to do that as the kids get older. This is his reason for wanting to leave. The problem: due to his economical status he is unable to get a place of his own right now with the four children in North Carolina. His family in Oklahoma is willing to help him in Oklahoma. His fear though is if he leaves and takes the kids his wife will file kidnapping charges against him. She has done this before. He feels the children are not safe with her. What are his options legally? What steps should he take to ensure the safety of his children and ensure that he will not be charged with kidnapping? P.S This may not matter but he is active duty SSG in the National Guards and is ex Army. So anything legal against him could affect this.

Thank you for your time.

If he feels the children are in danger then he should file for emergency custody.