If you can take her out, then I'd take her to a place like Radio Shack to see the phones for herself. This way, she'll be able to pick the one that meets her needs. If she can't go out, then I'd go and see them myself and ask the salesperson which phones have the largest fonts? Also a backlit keypad, or numbers big enough that are lit (LG phones have this- hubby has the VX4400). Also, I'd check for the largest buttons on the keypads. Try to find a simple one, without all the bells and whistles, which she won't want to use, and pay for either. Simplicity is the key in this situation. My mother is older, but even though her eyesight is good, she is still scared of technology. A lot of people are in their 70's on. So don't get discouraged, just be patient with her and it will be fine.
I am looking for a cell phone for my elderly mother. She is almost blind and has arthritis. We have tried a Motorola 120C but it really doesn't work for her in many ways. Any suggestions?