One thing that happened close to the end with my mother was more than a bit unsettling - she got very afraid of being considered 'mad' and of being 'locked up in an asylum'. Which is actually a fair description of an aged care home, but her mental picture of such places was very very out of date and she was very very hostile. Think of all the horror stories of Victorian era 'madhouses'. Like Bedlam etc. Faced with that prospect, she got very very hostile to the thought of being 'locked up'. It's possible your mum has a similar weird mental image of such places too. And would rather die than allow that to happen to her.

When push comes to shove, though, it is in the end her decision.