She was in hospice care. I would surmise she died from whatever reason she was in hospice care. As someone else mentioned if the power company is informed of vital medical need they will not shut off the power. Also I believe having her transferred to a hospital was an option.
Not sure a hospital will admit after someone is on hospice.
The thing is I have cared for several very ill loved ones over the years and the truth is I would have figured out some way to get her oxygen. The concentrators do work better than tanks (my opinion, no idea if med. research shows that) but I always had tanks in case I needed them. So I would have had her on oxygen while I figured out a way to get electricity to that machine. Extension cord to neighbor, borrow or buy a generator, hook up to someone’s welder...something, anything. I would have called ambulance and let them help me get oxygen- it was an emergency obviously. I would not have quit figuring out things until I had her on reliable oxygen. Fact.
I think these folks just sat and waited for electric company to turn the power back on. I find that real hard to believe but some people will absolutely just wait for others to do something even in an emergency. I was raised to just do what you have to and get something done ASAP.