Well, Prometka, as for myself, I think more in terms of things I use all the time, that have increased in price and that constantly have to be replaced like thread, hand sewing needles, blades for rotary cutter (if she has one). I think of a pack or two of very pretty buttons, a yard of pretty fabric you think she would like or maybe a pattern she mentioned she would like (either for sewing or quilting.
And I LOVE my extra fine, 1-7/8" long, glass headed pins that flow into fabric like butter and can be ironed over. A yard of light weight interfacing? Maybe fill a small basket with little items. Whatever you get your mother she will love it because you put so much thought into it.