You are such a sweet friend to want to help your friend in a time of need--and to look for practical ways to do just that! I lost my mom to a long battle with cancer just within the last year, though I can't imagine watching a spouse battle such a progressive disease. I can tell you what helped our family most through our difficult time.
Email and e-cards are nice, but nothing compares to getting a REAL card in my mailbox. Knowing my friends took the time to choose a card for me and write a message made me feel very supported. Phone messages and emails were helpful too, but there was usually a need to respond (often when I didn't feel like it or didn't have time).
Everyone processes grief differently, so you have the unique task of figuring out what specific things would help your friend most. Many people (especially men), even when incapacitated, are reluctant to let others take over their household chores. At the same time, there will be practical needs in their home which will need to be met. Ask your friend what they need and go from there. If your friend is reluctant to ask for any help, then you will have to stay close enough to her to sense what they need and how much help they are open to. Obviously they will need more help as the disease progresses.
Meals were extremely helpful for our family. I remember one friend who brought over a basket of breakfast items. This was different than the usual evening meal, and it was a extremely helpful! It saved a few trips to the store. Evening meals were extremely helpful too!
Many people would not want friends to come and clean their house. It would be just too embarrassing for me (my house is a mess), and I'd just feel weird about it. BUT, if someone were to send me a gift certificate for a cleaning service (one that's prepaid), I would use it!!! This can get expensive, but if you have other friends who are willing to chip in, this would be a good way to meet a practical need for your friend.
A few things that seemed to make things worse... We had a few friends that just seemed to disappear when things got progressively worse for my mom. I now know it was because they were afraid to interfere, but their silence was taken as a sign they didn't care. My mom went to her grave thinking one of her closest friends was mad at her, because she disappeared the last 6 months of her life. It helped me when I had friends who just let me talk through my fears and my grief. Hearing advice of any kind just made things worse. I just wanted to know I'd been heard, and that my listening friend cared about my pain. My feelings were validated with statements like, "I'm so sorry you are going through this" or "I know this is a difficult time. I can't imagine going through it, but I'm here for you if you need anything."
Hope that helps a little!