We've been dealing with a similar situation for the past few years with both parents. My dad's mental state is ok but physically he's been in and out of hospitals for years, including two hip replacement surgeries in the past year, and my mom's memory has become a big problem.
In addition to the good advice from others here regarding getting a good estate attorney and POA, we've found that dealing with Medicare is the biggest of issues. While they aren't technically death panels, Medicare does a lot to make a person believe that the death panels really do exist. A lot of care decisions end up being based on criteria that have nothing to do with what is best for the patient.
For example, Medicare stopped paying for my dad's post-op therapy after a set number of days, even though his recovery was going a lot slower than the average (he's 88 and healing/recovery takes longer at that age). They tried to discharge him from the rehab facility, which would have been a disaster since he couldn't even go to the bathroom on his own at that point or move around the house.
We fought the hospital's Medicare people hard and were able to get them to bend the rules to get a longer rehab stay for my dad, but they still ended up sending him home too soon. And, of course, that led to another fall within a month that got him his second surgery. After that, we were exceedingly aggressive in pushing back against the Medicare rules.
If you find the right hospital staff and are persistent, you can get a lot better care out of Medicare than they'd otherwise authorize. Don't be afraid to push hard, argue, coerce and do whatever else it takes to get what you know is in your mother's best interest. You won't offend anyone and it's the only way they provide what will be in your mother's best interests.
