My son's father is deceased. My husband is going to adopt my son. Will my son's biological father's family still be entitled to visitation once my son is adopted?

I've moved your thread from Adoption to Family Law because (it seems) you are asking about the LEGAL aspects of adoption, not the emotional aspects.

Could you please clarify your question?

That's going to depend on a LOT of things, including where you are located.

As noted whatever legal rights that have will depend on location. ANY question on law needs to include your general locale as laws vary by area.

However, what does the law matter? Why would you prevent them from being part of their grandchild's life?