There are also senior in-home care options, but even at 10-12 bucks an hour can get kind of expensive even at part-time.
Does she have to have someone there all the time, or would it be possible for her to be by herself for a few hours at a time? With tech, like Life Alert, Alexa, smartphones, etc., there may be opportunities for her to stay by herself for a few hours a day, and that, with a combination of your time and possibly a senior care agency, you might be able to find a workable solution.