Your company once or twice a week. Trips to your home a couple of times a month. Could you find a group outside the nursing home she would be interested in like The Red Hat Society? Card playing, Garden Club. If her eyes are not too stable perhaps a larger screen TV. New shoes, a new outfit since she can't shop too well are always appreciated. A spa day? A computer for company and games and keeping in touch with the family via Skype?
Of course gifts always depend on the person's taste. If you are looking to do some brainstorming, check out http://simplyhisandhers.com for some ideas. Simply His and Hers is a web-based magazine featuring the best in simple and classy shopping ideas for his and her fashion, entertainment, and home.