So I take it your discussion was that you would get her an apartment, pay for it with the understanding that you could come and go at will because you are paying for it? Is that right?
On one side I see your position on protecting your financial interest and the simple solution to that is DO NOT PAY FOR AN APARTMENT FOR HER.
On her side I can see how intrusive and controlling that would be and I wouldn’t like it either.
You can’t have it both ways mom, her out of her hair in her own apartment and you trying to control her, it’s never going to work for either of us. It hasn’t this far has it?