I'd have a heckuva time bugging out with my piano in tow. That's the only instrument I can play well. I'm trying to learn the ukulele these days - my first stringed instrument.

But a uke is not small enough to bug out with, unless you've got a big vehicle and extra room after all your other gear is loaded. A harmonica sounds like the way to go for disaster situations. Small, and I assume they're pretty sturdy as well. Unfortunately, for me, I can't say for sure if I find the harmonica pleasing, or annoying. Maybe I just haven't heard someone good enough playing one. I think the harmonica might be like a violin. When an expert is playing, it's beautiful. When your kids are trying to learn it, you want to run out of your house and jump off a cliff.

But back to the original thought of this thread - music DOES soothe me. I can be in a bad mood or stressed out, and after a few minutes playing the piano I am all settled down again. That's when playing something I can already perform. Learning a new and difficult piece is not always relaxing at first!