My little boy has special needs as well. The biggest thing you can do is be her friend. I haven't personally experienced this, but a lot of the special needs mommys I know have seen friends drift away. The mom gets caught up in all the things that her child needs, forgetting that she has needs too. The friends just don't know what to do. Offer to watch her kids for a bit so she can go shopping by herself, or take a nap. Encourage her to make time for some self care (coffee with a friend, a hair cut, etc). Simply be willing to listen even if you have no frame of reference for her issues.
Getting a diagnosis, even when you expect it, is tough. The day we went to the doctor for an official diagnosis, I preemptively took the rest of the day off work and arranged to go to the zoo with my family. I figured we could either celebrate or distract ourselves with some fun.
After taking a few days to assimilate the bad news, I was then able to start being more proactive about my child's care. Getting a "label" opened all kinds of doors for us. We were able to get into an Early Start program and finally get the therapies my son needed. I was able to connect with other special needs moms who knew where I was coming from.
If your friend is in the US, the program she needs to look into is "Early Intervention", sometimes called "Early Start". There are links to resources in each state here: http://nichcy.org/babies/services
In my state, the under-3 set can receive therapy in-home. This is fabulous when you see five different therapists weekly.