I have REI "Ascent" Compact poles (Compact is for shorter walkers) that I use for hiking, and I am about your mom's height. Most poles will work for her height; it's the really tall people that have to make sure they get poles that are long enough, as you typically lengthen them for going down a big hill and shorten them for climbing. Mine cost around $99, and I love them. Bought the add-on rubber tips to avoid marring rocks on the hiking trails as well. My DH has the same brand but in the regular length. And we aren't "old", we just like them for the extra stability they provide on rocky trails. They help the knees as well!

Emily

P.S. You can see a couple photos of me using them last weekend in the mountains in my blog (link below). Click on the photos to enlarge 'em.