Today’s question takes us (again) to the world of Philip Pullman‘s The Golden Compass. Or better yet, the movie version.

“does billy costa ever get his deamon bac[k]”?

First, honey, it’s daemon, not deamon.

Then, to answer your question.

In the movie version, Billy Costa is found in this shack, by Lyra and Iorek, and he’s almost dead from hunger, cold and the loss of his daemon. Lyra and Iorek take him back to the Gyptians, and his mom. 
Their world is like that: A human cannot survive without his daemon. When the daemon dies, the human dies and vice versa. And when they get seperated, like Billy Costa got from his daemon in the movie (which were the experiments they did in Bolvangar), none of them can really survive.
So, Billy Costa dies, and so does his daemon, if she wasn’t dead already.

I’m sorry.

As usual, I can only urge you to read the book. Not the least of reasons would be that Billy doesn’t die there [as far as I can recall, I might be wrong] (because it isn’t him they find in the shack). But it would definitely explain everything better than the movie did.