My husband and I had a house fire situation last year (and while it wasn't a total loss, we did lose a lot) and honestly one of the most helpful things everyone did for us is give us a bunch of gift cards for restaurants. We had to stay in a hotel so we couldn't do much in the way of cooking, and being able to go out and eat decent meals without having to worry about the cost was beyond helpful when our stress levels were pretty much constantly cranked to 11 and we could barely think of anything else. (Just make sure the gift cards aren't for any places that might require "dressing up" since they probably don't have the ability or desire to do such a thing.)

Other than that all you can really do is wait to see what they need and be there to help with it if you can. Everyone else seems to have it covered with the advice about family photos, not saying stuff like "It could've been worse" etc. Honestly the Red Cross is pretty damn thorough with providing most of the other kinds of resources that they could ever need. They even gave us information on how to get the horrid smell of smoke out of our clothes.