Reply #13: A friend of mine had a similar situation with her dog.

[Dover]

Ordinarily she'd let her elderly dog out in the fenced yard and the dog would
do his business. But as he aged he started messing in the house and so she began to isolate the dog in a particular area. Then it occurred to her to try a new routine. She took the dog on a fairly long walk in the morning and in the evening and for some reason (maybe the smell of other dogs or renewed interest due to change of scenery), he started doing his business and the problem was solved.

If you must keep her in the back hall area have you considered putting a heater in there? Either a regular space heater, a doggy bed heater or a ceramic bulb heater (that fits in a shop lamp...found at pet and reptile pet stores). I have some outdoor cats that stay toasty all winter with a heated
pad beneath and a ceramic lamp above.

Caring for elderly or disabled pets can be so hard.
I wish you both well.