OK, so I need suggestions.

My grandmother's 97, and needs a new bike. She rides 3-4 miles a day, and has for most of her life.

I've been keeping up with her old 70s Schwinn Cruiser, but it really needs to be replaced at this point- there's only so much I can do.

I'm a bit worried about her riding, however, and had been thinking about recommending a tricycle- it might help her with balance, and it should be easier to get on and off of, something that (although she won't admit it) she's been struggling with more lately. Anyone have any opinions on whether this would be a good move for her, and if so, some suggestions of trikes?

I also need some advice on a good cruiser-style bike for a very small lady- I mostly do, well, every type of bike but cruisers, so I have very little idea what to look for.

She doesn't love shifting, but she got used to it when she was racing back in her 80s. I think she'd prefer a single speed, coaster brake though.