This is one application I have thinking about for a very long time.
Creating some kind of interface that looks very physical (intuitive) could be the way to go. I am thinking about communicating with pictures.
One framework that could be extended to do the job is the RPi-InfoScreen project. There is no ads, stuff stay exactly where you program them. And it is touch screen only.
As the Pi is cheap you can dedicate a Pi to just one thing and put it on a logical place in the home.
Also have a look at the Pi fruitbox project. It is a jukebox that mimics old audio record players. Easy to use for elders.