Bad news today :-(

I am sorry about your friend and hope that he is at least comfortable.
With regard to fund raising, it will depend on where you live and what the laws are there because they are very strict here in Australia. There are all sorts of activities you can organise, depending on the law of course, and they include a Dinner/Auction. You try to work out some sort of deal with the restautant or whever you plan to hold it and then charge people a little bit more. For the auction you get businesses to donate things or even people to do gardening, house cleaning etc and these are the things you auction off.
Depending on where you live again, large or small town, then you can always organise a massive car wash where you charge everyone so much to have their car washed on a Saturday. A bit messy and you will need to advertise it widely as well as have lots of people there who will help.
One final thing, the 6 months might not be right. We have a very dear friend who was diagnosed 5 years ago and told that he had less than a year to live. He is still alive and is very frail so doesn't leave home but with medication he is still with his family and they are still enjoying having him around. Right from when he was first diagnosed, he was positive about the whole thing and said he had things to do first. :)