Hi @LostAngel, that's great you've had someone be so supportive of you throughout what sounds like a challenging time.
I guess there are lots options for what you could do! Personally I'm a fan of just honestly communicating how much someone's support has meant to me and how much I value them; and likewise when I've been on the receiving end of that honest thank you, it's made all the support I've provided worth it.
Other options could be getting them a small gift? Helping them out with something they might need help with which you can do, for instance- gardening? Cooking them a nice meal? These are just some ideas- you'd have a much better idea of what this person might like or need than myself.
In saying this of course, we are never obligated or expected to do things in return for people who've supported us. But I can also understand why you'd like to do something nice as a thank you for the level of support they've given you 💕