When I was diagnosed with cancer, the things the helped me most were offers of help with everyday things. Some friends brought food while I was being treated, or sent gift certificates to places where I could order things online, to be delivered. One friend came over and spent a few hours weeding my front garden, and offered to do my laundry. One friend volunteered to drive me to my doctor appointments, and visit me every day while I was in the hospital, to see if I needed anything. One emailed to tell me that if anything happened to me, she would come and get my dog, and take care of him for the rest of his life.
I also had friends who said that if I needed anything, I could call them. That's not as helpful as it sounds. Being sick makes you feel very vulnerable, and it's hard to ask for help. The best help I had was from people who listened when I talked, and read when I posted online, and raised their hands to say that they could help with whatever was a hassle that day.
There are so many things that you have to deal with, and take care of, when you have a devastating illness. Not having to deal with some of them made my life easier. So, think of what you can do for this friend to ease his or her burden, and do it, or arrange it, or organize it.