Couldn't resist butting in to this thread because CBD has helped my mum with the same problem. I would recommend you try the edible oils, the ones WITHOUT any THC (i.e. Hempelf, but many others are available) first of all.
I'd be a bit concerned that THC oil would have recreational side effects that your mum wouldn't want.
People are cynical about CBD, but it has helped me and many others I know, with sleep and various medical conditions.
Good luck to you and your Mum, and many thanks to her for working as a nurse to help others.