I happen to believe that everything does happen for a reason, because in general that makes more sense to me and there's no proof either way; but in the middle of the storm it's an extremely difficult position to hold.
What people actually do need in those situations is presence, someone who listens; not good advice.
I'd rather say something truthful and of support, backed by real action and history if actual support instead of saying something trivial. I remember a friend told me such thing when I was grieving (something along the lines of "you have to pray" or something) and I blurted "oh really? so I wasn't praying. so it was my fault? so I needed YOU to remind me at my worst times? what happened to reason?"... he stopped talking to me for few months, we are still friends... but if he hugged me and kept quiet just the looks of their face feeling sad for me would have been the perfect support I needed. Sometimes silence is way better than telling a religious lie to "comfort me".