Big screen mobile phones
Till now, there isn't a single mobile phone with a large enough screen and keypad for old people. They still have to get their reading glasses out of their pockets and make their way through complicated menus to make a call.
Even if there is no emeregency, I don't enjoy watching them search for their reading glasses, put them on and start pressing on several tiny keys at once with their thick fingers.
And this [Sagem phone|http://news.bbc.co.uk/2/hi/technology/4566809.stm] is not a solution. It is still a small phone with tiny fonts and tiny keys.
I would suggest they make something with dimensions similar to this: