Ended up getting a doro 612 for my mother who suffers from arthritis, and some loss of hearing and vision. For £40 sim free this looks good. A reasonably attractive clam shell design ensures it's turned off when put away, the keys are large, volume is loud and clear, screen good for reading and menu easy to use. It has a long standby and a basic camera. The emergency and quick contact buttons are excellent. And it comes with a dock to slide the phone into, rather than having to fiddle with micro USB cables. She doesn't want internet so that's handy as this has no internet connectivity. She doesn't use headphones so the non std headphone socket isn't an issue, though it has Bluetooth.
She has previously tried an iPhone, various android phones (configured with big buttons) and a Nokia 520. The issue has been keyboard size, swiping left to right and the need for frequent charging.
Proof will be in the using, though I suspect this form factor with the ability to look up bus and train times will be what she wants (though she hasn't used these previously when installed). Now that many bus stops have NFC to look up the next bus details, NFC could be handy too.