We live in California, the biological father is in prison and is not in the birth certificate and my husband wants to adopt my son and my son wants too be adopted my him. Can my husband adopt him ?

Yes easily if the bio father will sign over his rights to allow the adoption. If he will not sign, it will be harder and cost a lot more money, since you will have to convince the judge to take away bio fathers rights on various reasons, showing it is for the best interest of the child.

And since you didn't put him on the birth certificate to start with, this will be much harder, as you have to ESTABLISH paternity before you can even start the adoption process.

Get a lawyer. While you CAN do adoption without a lawyer, you can also set a bone without a doctor. I don't recommend either.