Mom has pneumonia and is in transitional care. What's the best way to support her?

How low can her O2 sats get before she needs readmitted to the hospital? Mom was in the hospital for 6 days with bacterial pneumonia, and released to transitional care because she was very weak and unable to go home. She has been there about 5 days now. Friday I thought she had turned a corner for the better, but tonight Monday I went in to see her and she was burning up with fever, not very alert and although she knew where she was, she was wasn't making much sense when she talked. I've seen her like that when she was overmedicated and sick...kind of like she was time traveling in her mind. She said her O2 sats had been 57 this morning! She is normally on 3 litres and stays around 88-95. Considering the pneumonia, I would expect her sats to be on the low end of that right now, but 57 is downright dangerous. They cranked her up to 6 liters and left her there all day, and her sat was 86 tonight on that. I had to round up the charge nurse to see what was going on, and he got the respiratory nurse to come in and assess her. I'm worried that her sats will go down again...shouldn't they have taken her to the ER or at the very least called me if it was that low? I'm worried that she'll have organ failure and brain damage if it gets that low again and no one notices. At least in the hospital she's monitored continuously and an alarm goes off when it gets low. I just wish I knew how much to expect of this facility, because I can't be there 24/7, obviously. She's feeling so awful, aches all over and can barely move...can't even turn herself over to her other side in the bed without help, and it seems she's getting worse instead of better. What's the best way to support her right now? The nurses are very nice and attentive when I ask for something for her, but I worry about when I'm not there.