What do you say to someone who's just lost a loved one? Really there is nothing to say. The closest thing is "I am sorry" or "I'm here if you need me." But I think the best thing is to just be there, listen, and not say anything.
My husband did that for me. The night of Grandmom's service he just held me while I sobbed. He didn't say anything, just held me. That's what I needed.