What a great thing for you to do!
If she's artistic, there are a lot of "adult" coloring books nowadays. They are absolutely beautiful. If she loves creating but needs a bit of inspiration, there are books on Zentangle or Doodling. They are great fun and very creative once a person gets the hang of how patterns can be used to create interesting and beautiful art. I do birthday card nowadays using the Zentangle method of patterns and I find it very Zen (in other words, very relaxing and mindful!). I've found the books on Amazon and at Michael's Craft stores.

All she needs for the actual drawings are thin felt tipped pens. I use Sharpies or some of the other brands now offered. A lot of Zentangle drawings are done in Black & white so not a big cost in buying writing/coloring utensils. Hope she does well and I'm glad to hear that you're doing well too.