First it is great that she has someone in her life that will be there. Next no matter what happens in court, in her heart, he will always be the father.
Yes the bio father has rights, and prison for the bio father as a reason depends on where you live, in some places it is a listed reason, in others you will have to prove it is for the childs benefit, while that should be easy, it still has to be proven
So the first thing your attorney will do is try and just have the bio father sign over his rights, to allow the adoption, this will be easier, faster and cheaper. If not, the attorney will file to force the rights of the bio father be taken away to allow the adoption.
It should be possible with such a long prison sentence, but it will still have to be done though court.