How old is she? If she's 40ish, first sign of aging or diminish fine line stuff probably works. If she's 50ish, actual anti-aging or things that helps with hormonal aging/wrinkle would be good. My mom had great success with L'occitane Immortelle, Murad Age-Resurgence, and Shiseido Wrinkle Resist. I think there's kit out for all 3 lines, and suggest read the description and filter by age to figure out which ones are for you. Depending on how much she like skincare, an enzyme mask is gentle and helps with dry/dull skin, I think Ren have one for mature skin.
I've also heard good things about Algenist, and Peter Thomas Roth un-wrinkle and PM retinol serum stuff. Retinol is good for antiaging but it's tricky and you have to be careful of usage, my mom's the no fuss type so I skipped that. If she have dry skin, then she should use serum and moisturizer (my mom have super oily skin, so she is only willing to serum in the summer and moisturizer in the winter). Mmmm, what else....ah, if she is getting dry skin or patches even with the serum and cream, try getting her a beauty oil like Josie Maran Argan oil or Tarte Maracuja oil. After serum/moisturizer, just rub 1-2 drops into the super dry areas like the cheeks etc, and she should be all set. That's all I know about anti-aging skincare up to this point.