I have been in this situation TWICE with my NPD, alcoholic MIL.
The manipulation, arrogance and delusion and entitlement was v hard to cope with.
Her original family home was just vile. She accumulated 10 stray cats that shat, pissed, vomited and shed hair everywhere. There were un-emptied litter trays with overspilling “contents” everywhere. Add to that standard “alcoholic squalor”. She hoarded everything - every, single child’s birthday and Xmas toy from all 3 children from 50 years ago.
It got so bad and she wouldn’t let anyone in to help clean, sort or tidy. She would get quite nasty about it. She wouldn’t even let us get a plumber in to fix the boiler as she wanted to tidy it up first (never happened). This went on for 3 years where she had no hot water. She had shed loads of cash.
We got her out by playing to her NPD. We look her on a tour of some stunning high end new build apartments to rent in a v posh neighbourhood. She was dazzled and moved out with just a suitcase the next month. We then cleared, renovated and sold the house - used her money to hire professionals. Saved a few bits. By the time she had moved she never asked for anything else (doubt she could remember any detailed stuff).
We got a cleaner in from day one in the flat to keep on top of it - most of the cats didn’t go with her and she trashed it a bit and lost her deposit.
We then bought and renovated another property in the nice area once the original house was sold. She quite enjoyed lording it over us and not doing any of the work - but that suited us as we were winning the war.....
She then over the next 6 years made an absolute mess of that next house - again more cats, now herself in-continent (as well as the cats). Again cleaners from Age Concern come in twice weekly before she finally went into a care home.....again only with a suitcase a a couple of bits.
Again just cleared the house with professionals, re painted and sold it.
So my advice would be do not engage in trying to persuade her to sort it or be manipulated around conversations about you actually doing it....these will never happen......because they have never happened and will just drain and frustrate you. Don’t let her yank your chain.
Offer one solution. She moves out and professionals sort it. She pays for it - you are happy to book a reliable firm etc.
But just let her get in with it - she sounds happy, mobile skipping around. Really not worth the fight. Just wait for things to inevitably evolve.