oh Wools, my heart goes out to your friend and her family at this terrible time. It happened to us last year.
Right now, just be her friend, and let her talk, cry, shout and scream as much as she wants/needs to.
People don't ever "get over" these things imo, as such, but you learn to live with it, and very slowly you learn to smile again.
I'm sure she's been directed already but Sands is a fantastic place for support as is here.
Your friend needs to take as long as she wants to be with her baby,m and take loads of photos, memories, hair, handprints, etc. I'm sure the hospital will help with all that, they are normally very sensitive.
I will light a candle for their angel. Please pass on my condolences.