The underlying problem is the lack of boundaries. Moving away does not solve that problem. Only setting and enforcing the boundaries will solve the problem.
Distance and cutting off contact (restraining order if necessary) are profoundly effective boundaries.
Psychological and emotional boundaries are required. Cutting off contact by itself is not enough. You have to communicate that you are cutting off contact. That's what establishes the boundary. In many cases you won't get a restraining order if you haven't established that boundary. The restraining order is a tool for physically enforcing an established psychological and emotional boundary.
Downright psychological abuse.
You can't solve a boundary issue by not dealing with the boundary issue. At best, you can avoid it and hope it's no longer a problem. The underlying issue still remains.
Slaughtering the cows would be like... selling her car so her mom can’t use it. Her mom can’t hurt the cow anymore, sure, but there’s still no fence there.
In contrast, telling her mom “No, you can’t use my car” would be setting a boundary. But telling her mom “I don’t want you in my life” would also be setting a boundary. These are just two different fences. In both cases, the cow/car are just fine.
It's easy enough to tell someone to never contact you again. But if you see them daily as you prepare to commute because you live next door, a lifetime of social pressure to not be so rude as to ignore people is likely to get them to slip up and at least say "good morning!", even if they want to respect your boundaries (and definitely if they don't, and are looking for an excuse to trample all over them while perhaps pretending otherwise!) If you share a common living space or other "shared business" it's even worse, as there's also the completely understandable pressure, if not outright need, to resolve problems involving that shared business.
Moving is an action that can help disentangle you from shared business - be it common living spaces, shared fences, shared neighborhood issues, etc. - and help dismantle habits that would undermine your boundaries.