I wouldn't get a puppy. Too much energy for your old lady to cope with.

A mature (4 or 5 year old) dog might be a good fit, however, if your old gal likes other dogs. Then she'll have another friend in her twilight years, one that won't stress her out the way a puppy might. And there are lots of older dogs that need a good home. And if you get a 4 or 5 year old dog, you can still add a puppy to the mix after your old lady passes, if you really want a puppy. The older dog will help train the puppy.

Bottom line though, your first priority, IMHO, should be what is best for your old lady. Her last days should be comfortable and peaceful. If she is NOT dog friendly, probably best not to get another dog, even an older one.