If it was me, if there are any hens left, I would put up some kind of quick shelter with a heat lamp if possible and leave out food, water, and a roost pole. In other words, just kinda take over. Chickens are going to go where the food is. Obviously, your neighbors are not interested in taking care of them anymore. Mostly, they need enough calories to burn to keep warm and a place to get out of the wind.
As for the rooster...good luck with that one. If he wasn't mean he would be worth saving....I guess. Even if you save him, you have to deal with him beating up your birds.
It's not that cold where I live. It's by the coast. We even have wild pheasants. The winters are long, though.
Oh and btw, I have a couple Marans hens and they are oblivious to the cold. I processed some Marns roosters this fall and I swear they had twice as many feathers as my other breeds. When it is nasty out and there are only a couple of hens out in the run, you can bet it is the Marans. Last month one Marans roosted out in the run for the night while it was snowing. In the morinig she had ice on her back. She was fine...just decided to spend the night out.