Hi N.,
I can understand your situation!
One thing I can suggest, that can also be beneficial if she is open to touch is Reflexology as this is so very good for Diabetics. It improves the circulation (helps her heart, and her feet!) and so much more! Even those that cannot 'feel' their feet, can feel something when they receive a session. It typically takes at least six to notice a dramatic change, however after the first she would know if she would enjoy it.
Usually, diabetics do not do well with 'warm' on the feet as this poses a danger to the nerves as they do not sense things as well as we do. So she is not trying to 'complain' with that gift. It was a great idea as it does help the pain for most of us! :)
If she cannot walk too well, then it sounds like you want to have someone that can go to her, not have her go to them (or if you can take her. So make sure you choose the person wisely. (if you go this route.) ABMP has a great selection of therapists and you can enter your information in by zip code to find what you are looking for. Some therapists even have a website you can access for more information.
Best of luck! I am positive you will find something! :)