What can my daughter do?

My daughter is from Texas and my son in law is from Utah. The relationship has deteriorated and they are always fighting and yelling and now it had gotten physical where my son in law gets tied ofl istening to my daughter so he chokes her down and pushes her into things. Big problem, they have 2 young boys under 5 who see all this. She has not filled a police report when he abuses her because he threatens her. She has pictures of bruises but never used them. They are always yelling and fighting in front of my grandkids where now the boys hit their mom and call her names. She is the primary parent. She takes care of them she teaches at a day care and the kids go with her every day. The day works 6 days a week gets home at 7 at night and spends no time with her or the boys. Is tough listening to her try to deal with everything by herself on the phone. She wants to come back home and live and go to school. She is about to leave him because of lack of love and fighting in front of boys. He brings home beer every night and himand her drink it he tells her if she tries to leave the state he will say she is an alcoholic and she will loose the boys and she is scared to death she doesn't have any police record of anything like that but she fears she can't leave the state and come home the children have spent equal time in both states but they have been inn Utah for a year. She's worried if she leaves he will file them she will have to go to Utah and live forever and she has no family or support in Utah plus cost of living is higher . Recently she caught him on a saying suite trying to hook up with women and he was watching porn in front of the 2 year old boy while on the computer. His mom says she had family members that are involved in parents who try to take kids out of state and for her to go ahead and try she will lose the boys.