Honestly, I would have hated that. It’s not really something I wanted a gift to commemorate in the way that you’d write in a journal. I definitely wasn’t up for journaling. Nor did I do much reading during treatment (too tired!).
Things that were useful - anything warm! I was very cold. I got myself an electric blanket that I still use now, so a nice thick blanket.
Something she can use to entertain herself. So this may be a book, like above, or audible credits, or new headphones to listen to podcasts or stream Netflix. I’d go for gift card rather than choosing a book so she can pick out something herself, unless you know she specifically really wants the next book in a series, for example. Nothing inspirational though! Nothing annoys me more than everyone without cancer constantly telling me to “think positive!”.
Some of her favourite treats, tea, matcha, whatever she loves. One of the best things someone gave me was a box of brownies. They really cheered me up. Also skincare, ideally a voucher for it. It does weird stuff to your skin.
Also don’t forget that cancer is a marathon, not a sprint. Get her something in a few months time too when she’s in the thick of it and truly feels awful. People all forget about you after the first month or two and stop asking how you’re doing or looking after you. Also it’s far off, but be led by her in how she celebrates finishing. For most of us, finishing treatment isn’t the end and it’s actually much more scary after you’ve finished. Mine came roaring back 2 weeks after treatment ended just as everyone was like woo hoo! You’re all better now! And I had to constantly point out that I definitely wasn’t better, but everyone was kinda bored by it then.
It’s very kind of you to think of her though!