PollyParrot I do hope your MiL is still in Hospital, don't let them discharge her without a full assessment & care package. I'm glad your DH has spoken to Ward Sister as they only have what your MiL has told them unless you speak up, get name of Social Worker, make sure assessments have been done, Occupational Therapy will need to assess what equipment she needs & whether she can manage.
When my DH was diagnosed with terminal cancer I was asked if he could come home, he was bed-ridden, this was just before Christmas, luckily I was with the Pallative Care Nurse when this was suggested, the look of horror on my face must have shown, my own DM had come for Christmas (occupying spare room) & she had her own health problems, he was quickly moved to a local Nursing Home where he died less than 2 months later
My own situation last year after 5 weeks in Hospital (severe Pneumonia), before my discharge I was assessed by OTs to make sure I was fully mobile (I live on my own although DD is only 20 mins away she has DGS & her OH to care for). Hospital Social Worker also discussed my return home & OT came a hour after my return home with all items I may need to make my life easier (raised toilet seat & shower stool), some equipment was not suitable in my small home but I manage well.
You must emphasise your own position & health problems (worst case scenario - can't assist our MiL to walk etc, can't be there 24/7), maybe it's time for a Care Home, it sounds like whatever you do will be wrong
Fingers crossed but don't be pushed into something you can't cope with