I know I'm picky - an only like YLI GLAZED COTTON HAND QUILTING THREAD. YLI has threads for different purposes.
Ask your Mom what she would prefer and get that.
If she doesn't care - glazed cotton in important - it threads nicely and slides thru the fabric nicely. I do prefer YLI or Gutterman because the thread is a bit heavier. YLI is also cheaper than Gutterman when you're comparing the 2 spools and account for yardage. YLI spools have more thread on them.
Unfortunately, no one sells it locally, and i do have to order it online - but the place i get it from (Rose Rushebrook) sends it out quickly and i have it w/in a few days. The shipping fees are reasonable, too.