Were there other breakers to the left of the burned one? What condition were they in?
And the top breaker on the left side looks like some more melting is happening in the screw area.
At least some of the other breakers appear to have tripped during the fire...
Thermostat pic: Was this the point of origin? I've heard of a few LV t'stats causing fires. If not, what was the cause of the fire?
Waht a sad thing to happen right before Xmas....