x2
Since it was at night, it is not likely a hawk as they generally hunt at dawn and dusk.
An owl can and will hunt at night, but most would find it difficult to drag off a large hen so generally eat at kill site.
With the head gone and the guts removed, I too vote raccoon (although other animals could also be possible).
And are you sure she went out of the coop voluntarily?
I had a raccoon manage to break through the chicken wire (which keeps chickens in but does no good at keeping predators out), enter the chicken coop, and drag a hen out.
I locked up a bit later than usual (after dark...it was Christmas season) but miscounted birds not realizing one was missing. The next morning I found the carnage outside the coop.
Once successful, that raccoon came back night after night. He would even snarl in my face as he clung to the rafters of the run. He got 2 more of my best hens. We had to (legally) trap and dispose to get rid of him.
Lock your birds up tight behind wooden doors nightly, at dusk preferably, to protect them until the predator is discovered and properly disposed in manner available to you by law.
Lofmc