Two of the shortest women I know (4'11" and 5'0") ride bikes with 700c wheels. I set a Trek that one of them bought up with a new saddle. I'm almost certain it was a 48cm frame. I'm also pretty sure Georgina Terry, or her company, is still making women specific bikes and likely takes petite women in the 4'11"+ arena in her stride. I believe she also uses 24" wheels too when necessary. 26" wheels are, of course, an option and may well work for the o.p.'s friend. Not because she is short, but because there are lots of tire choices for the kind of riding a returning older rider might be doing. The women I know are doing club rides with the B group of 30 to 50 miles and 700c has just the right kind of tires for that kind of riding. 26", not so much.