Hi Ann,
I think Jackie has already gone to work.
She had real problems in finding a MTB to fit propery. At 4'11" (on a bad day) her first MTB, a Giant Sedona 14/15" was too high in the front and a bit long across the top tube. She has ridden a Giant Upland (see below) with no front suspension, with the seat right forward or the post turned around she "can" ride it, not a pretty sight.
The bike she fits perfectly is an Apollo Panther, a 12.5" boys bike with 24" wheels. She has semi slicks in 24x1.75 and a 11-28 cassette fitted, it is quite quick. She looks and is comfortable and is in control on the bike.
My suggestion is to keep looking at ladies frames in the 14"-16" range. Take your tape measure with you. Dimension "A" (Apollo) is the important one, 555mm is probably a little long, 520-*540mm may be better.
Apollo Marathon, Shoreline, Altura, Dimension "A":
http://www.apollobikes.com/sitebuilder/apolloproducts/files/27/ap_frame_geo_cross.pdf
Giant Upland,
*Sedona, Dimension "D": http://www.giantbicycles.net/au/cat...=popup&p
opuptype=geometry-image&modelid=9996