My niece leaves in Savanah Texas and her boyfriend told her that she will send her to jail if she take his boys to Ca. she wants to move back to CA, boyfriend does drugs

What is the custody order, what is the visitation order, What court issued documents are in place.

Most likely she can move, but boyfriend can fine to have the court order her to return the children, if she does not have court permission to leave

Sure there is, its called contempt of court. But it requires a court order to be in contempt of.

That's why Chuck asks about custody and visitation orders. If there no court orders providing custody and visitation then there is no issue of contempt of court and nothing to jail her for. However, if there are orders and she moves without court permission to where he cannot fulfill the visitation order, then she will be in contempt.

If there are not court orders and she does move without court permission, then he can file for custody and she may be forced to return with the children.

So her best bet is to go to court, show he is on drugs and a danger to the children and ask for sole legal and physical custody and permission to move.