What about this: http://www.trekbikes.com/women/wsd_p..._path/7000wsd/

The bikes you've suggested would be mostly fine for taking short rides or running errands. And if that's what your mom will use it for, they might be appropriate.

But if you would like for her to go longer distances - and you live in a place with either hills or wind - you should probably make sure that she has the appropriate gears to keep up. If every one else can ride up the big hill by calling granny, and she ends up walking her bike up because she doesn't have a low enough gear...she may not be enamored quite as much of biking.

I'm not a real fan of coaster brakes either, and certainly not as the exclusive means of braking. If your chain falls off, or if you chain breaks, you suddenly have no brakes anymore.