My 67-year old mother is doing some genealogical work in China next month, so I got her a flash for the digicam she bought, plus a spare camera battery, spare flash card, screen protectors, and an Ultrafire C3. I can't give her a knife or pepper-spray since customs would probably take it away, hopefully the light could be used to disorient an aggressor.
I hate shopping for other people unless they tell me what they want. Especially those without hobbies or for acquaintances. I got my girlfriend's mom socks. I swear that's what the GF said she wants. Money and a plane ticket for my sister attending Johns Hopkins U. Buncha stuff for the GF. Nothing for the brother, dad or other sister. They didn't tell me what they want.
Maybe get your mom a gift certificate? Does she like gardening? Cooking? Knitting? Extreme sports? Oprah DVDs? Books?