There is nothing more dangerous for a woman than leaving an abusive man, so make sure she has a restraining order, he doesn't know where to find her and she's given support in not returning to him because the leaving is so difficult.
A restraining order isn't always a safety net, and in fact in many situations can make things worse. It's a decision to consider carefully and be very thoughtful about. Sometimes, it is the right move. Unfortunately, other times, it can be provoking and to someone likely to plan an attack of some kind, they are clearly already willing to break the law so one more legal barrier is unlikely to matter.
As for how the friend can make money, the questions about whether she is clean and sober make a huge difference. She can try to teach English online, but programs with which I am familiar require a college degree.
If she's interested in working toward that, you could help her find scholarships and/or online programs.
Caring for children is seems like a fairly obvious choice, but finding business might take a while. This could either be an actual licenses business or just watching a child or two for a few hours between the end of school and parents getting home from work, plus evenings and weekends to cover for date nights.
She could also sign up for Rover or other dogwalking services. I don't know their rules, but it seems like she could take her kids along while she earns a few bucks walking someone's dog.
You can also help her find social programs for which she and her children might qualify. WIC, SNAP, housing assistance, local food banks, etc. All these things can help her get her feet back under her.
