If he's not close enough to her to know her interests and what she'd like I also suggest sending a card with positive comments, perhaps remembering things they did together way back when. Or send flowers. They are always appropriate.
If he knows her interests or hobbies send something related to those. I don't know how much energy she has. That might make a difference in what he sends. If she reads but hasn't much energy perhaps a book on CD, if she has a player. Most DVD players will play CDs. He could send her a gift card for a food treat. Or send her a fruit bouguet. I can't remember the company name or how to spell bouguet. lol
Note: if chemo is causing her to always be nauseous then food wouldn't be a good idea but I think that sometimes there are days without nausea.
I've had lung cancer and my cousin recently died from cancer. We both continued to live as much like we'd always lived making adjustments when energy or pain levels changed. My cousin enjoyed getting out for lunch with friends. He spent a lot of time on the computer and bought an e-reader. Those were his interests. Even when he didn't have an appetite because of chemo he still enjoyed eating with friends and liked for me to buy something special to try to tempt his appetite. A fruit bouguet would do that.
My cancer wasn't so serious but what is related to your bil's friend is the need for people to be sympathetic, yes, but to also treat me as the same person I'd always been.