We have had custady of a non related child for 2 years the mother is willing to sign adoption papers. The father has been in prison for 3 years. Does he have to sign also. We live in Tn

Generally, yes.

You should consult with an attorney in your area to be sure.

If the father agrees, this shouldn't be a problem. He is served with papers in prison and signs. If he refuses to sign you may have a problem. I assume you have an attorney to process the adoption.