help!!! is this just molting or..??

I have seen a chicken like that before in my flock and then the new quills came right in...so in my case it was just someone pecking someone's feathers out.

There may be a nibbler on the roost at night. Do you have lights on inside the coop at night all of a sudden?

It never hurts to consider mites/lice. Has the bald spot just occurred? If it just occurred and everyone looks wonderful except that one spot I would say you have someone nibbling at the feathers would be my guess.

 

When my chickens get bugs the feather condition starts to look poor (feathers look out of place, not smoothly groomed) and they look tired and depressed.

You can look under the wings and around the vent to see if you see any bugs. Or if you feel itchy at all when holding your hens.

 

You might have a feather picker. I've got one, here is what one of the victims looks like...

Sit out there with the chickens for awhile. If it is a feather picker, you'll know it pretty quickly.

I'd cover her bald spot with blu-kote. Do you have a hen apron? if so, put it on her, that may help until the feathers grow back. If you figure out the picker, pinless peepers on her may help.
Here is one other in an apron:

Mother was molting in the background there, the SLW, Cluck-cluck my feather picker is wearing the peepers.