Give them cookies...or hugs.

Hearty proclamations dipped in affectionate phrases spoken in a foreign language, french preference. Gifts work also apparently probably

Well since they're doing so much for you it's obvious that they care about you quite a bit so you honestly don't have to do much other than be there when they're in need. Though an occasional gift or some action that you wouldn't just do for anyone can go a long way.

I've been in the situation where I was the friend doing a lot and I didn't expect anything out of it, I was just happy to be there for them and help them enjoy life in general. They'd give me gifts and those were nice for a time but a few simple words were usually all it took to make me feel good long term. So it really just depends on the type of person they are, you should know them well enough to be able to show how much you appreciate them and what they mean to you. So it won't be too hard when the time comes and all that.

:O thank you c: