Sorry to hear...
My wife gave birth 7weeks ago, and I just simply cannot imagine the sadness your friend is going through. From father's point of view, it is extremely overwhelming, for the first couple of weeks, and I just wish either my parents(or my wife's) were with us to help. Thus, always offer him your help. This help doesn't mean to just ask what he needs. Invite yourself to be with him, offer something to eat, drink, washing dishes, clothing (yes, lots of baby clothing wash), even cleaning, baby sitting for a couple of hours, or walk with him and baby. I am sure any help will be appreciated.