What I get from what you have written is this man is not adverse to harming his child while he is striking his wife. How is it you know these things? She tells you, or you witness them? If you're witnessing them, call the police. If she is telling you anything like this tell her you'll turn them both in for exposing that child to an unsafe environment. She has no business working with people in need if she is willing to expose her own child to physical harm and the trauma of seeing physical abuse rained down on mother.