Can my husband claim Job seekers allowance if we are relocating?

It depends, they will have to ask him some more specific questions about why he has to move and they will confirm with his ex-employer. There's a good chance that he might get JSA, but they don't give it if they decide that he has left his job voluntarily and had other options, and just deciding that he wanted to move might not be a good enough reason for them. He can try of course, and if they say no he can appeal it, but try to get a plan B in place just in case he isn't getting any income.