That all sounds rather familiar to me, though it wasn't a stroke (to my knowledge). She wasn't actually diagnosed with anything, just regressed into acting in these ways over time. The hoarding and anger are especially familiar.

I had no answers and neither did any doctor, aside from the implicit conclusion of dementia worsening gradually. I suppose a stroke would have similar effects in terms of taking away the mind.

The only thing I could do was to be there for her, FWIW. At the time, I didn't understand much. Sorry that I can't offer any real answers, but you're not alone in dealing with this.