For an elderly driver, I would look at cars with a more vertical a-pillar than what's seen in a lot of gas saver or 'sleek' models. None of the 30 degree stuff you see on a Prius, Honda Civic etc. These pillars start getting into the way of visibility big time, IMHO. Combine it with an older driver's eyesight and reaction times, and you increase the likelihood of cut-off situations significantly.
I hink the Avalon makes a great car, but it will be a few years old at $16k. Evaluate if a little smaller car would not fit the bill. It is easier to maneuver and see out of. The Mazda 3 is great, but it is a little harsher and noisier than what she probably is looking for.
I would not even recommend a Chrysler to my enemy. That 200 looks like a royal POS, just look how they have the muffler hanging out half a foot out the bottom, for everyone to look at when following the car.
G