How to get away from a neighbor who has completely lost her mind and is now a danger to others.

Try giving your neighbor a couple of fancy style fidget spinners nicely gift wrapped to see maybe that might keep her occupied.

Lock your door, so she doesn't come in your house.
Build a fence.
Don't go to her house/property.
Move.
Put up a sign warning of "murder hornets".

Ring the police and have a word with them, record anything she does to you for evidence.  Police can always contact mental health workers. 

I guess one way to get away from a crazy neighbour is to move away but then the crazy neighbour wins, the other neighbors are still in danger and the crazy person is still a danger to herself. Usally calling the cops doesn't do much until its too late so I think you should get together with your neighbours and make a couple plans. A plan for possible ways that you can help her and a plan on how you can help protect each other (neighbourhood crazy watch or something like that). So walk softly and carry a big stick. Cheers!