Given the choices, I would definitely say a black and white eink kindle or nook.
She's got an ipad, which means she already has something that runs apps, has a color screen, etc.
The huge advantage to eink is that it doesnt cause eye-strain. reading is enjoyable again. magazines will look better on her ipad... but she's got an ipad for that, so no need to get a second color device that would be inferior to the ipad in many ways and compete for space in her hand. magazines can stay there, and books would thrive for her on the black and white screen.
I have a eink kindle, and would buy another one if/when this one breaks.
I might get a kindle fire one day in order to flash it and get a cheap tablet... but I wouldn't buy it to read on, no backlit color display can match eink for hours of strain-free reading.