If I have a cosigner for refianace home can I will them the house if I dye

Yes but they still have the responsibility to make good on the terms of the refi agreement they cosigned on. It would be so whether you willed the home to them or not. Consult an estate lawyer for specifics.

A co-signer is not on the deed and is just that a co-signer, They would have to make arrangements with the bank to take over the mortgage.