post sepsis syndrome help

Back in October my mom who is 71 years old, has MS and mild cognitive impairment (due to MS not dementia) got sepsis. She fell in the bathroom, tore her whole right calf apart, and had a swollen kidney. She did battle UTIs her whole life due to the MS but never went septic until that day. She was also battling cellulitis (she's had that in the past as well). She was in the ICU for 2 day and then in a regular room for about 2 wks. After that she went to a rehab faculty to work on her mobility. She was there for about a month. Since having sepsis, she never walked again. She is completely bed ridden (she walked every day before this & was always active). She also suffered from severe delirium. Her medical conditions got so worse from the sepsis, she had to enter a long term care facility. She has not walked since the day she entered the hospital and her delusions are incredibly severe still (4 months later). She thinks people are going to kill her, that people will hurt me, all kinds of heartbreaking things. I always reassure her that nothing is going to happen and how much I love her but it doesn't help. It's like a switch was flipped in her brain and one minute she was completely fine and the next she wasn't. And not to sound pessimistic, but I don't ever see her recovering. I don't think she'll ever walk again and I think her mental health will continue to worsen over time. My heart breaks for her. I feel helpless. I have a friend who is an EMT and he said its possible that maybe the day she went septic and was admitted to the hospital, she could have suffered some loss of oxygen to the brain, resulting in long term or permanent damage. Has anyone experienced anything like this or know someone who has? Any advice?