She has to try out the readers to see what works for her. Just check out the return policy for the ereader.
I became a huge fan of audiobooks for more than 10 years because I was unable to read. Fortunately, I can now read using an ereader, but I continue with audioboooks for more complex stories. Certain ereaders, like the Kindle Keyboard, allow text-to-speech which also helps tremendously. It takes a week or two to get accustomed to having your newspaper read by a robotic voice (clearly, I prefer an actor doing it, but I take what I can get).