Hello, Sad Daughter, and welcome to the forum. I'm glad that you found us, but sorry for your mother's illness. I, too, have cirrhosis from hep C, but am fortunately stable at this time.
Are they giving your mom Lactulose? That should help with any "brain fog" she may be having. You do need to keep a close eye on her in the NH, as they usually have just one doctor to cover all patients (basically writing orders for meds) and that doctor is not a specialist in liver disease. I would suggest that you get Power of Attorney and Medical Surrogacy, if you don't already have it. This way, you can communicate more effectively with the nursing staff and the doctor. Because of privacy concerns, it is next to impossible to receive any information unless you have these things in place.
Fluid restriction is not unusual if a patient has ascites and edema; however, it is a real balancing act and it does sound like your mom wasn't getting enough fluid.
I know you will get a lot of support and info in this forum, so keep posting!