This is the hard part when a diver goes missing: we simply don't know when to give up hope. We certainly don't want to give up before they do, but we do need to face the almost certainty that our friend Noah is gone. If you know Noah's mom, give her space. The last thing she needs is to hear people telling her they know how she feels. You don't. You're not even close. I lost my 24 year old son last year, and even I can see that there is no way to fully understand or appreciate what she is going through. The best you can do is to offer your sympathy and tell her that you couldn't possibly understand the pain she's feeling right now. Don't give her advice, not even about God, unless she asks you for it. Respect the grieving process as intensely personal. You'll be appreciated as a friend for that.