Q. When Jesus was dying and entrusted his mother to John, does that mean Joseph was dead?

Yes, most interpreters believe that Joseph had died and that Jesus, who had been responsible to care for his mother as the eldest son in the family, was asking John to take on this responsibility.
This shows us two remarkable things:
(1) Even at his time of greatest suffering, Jesus was thinking of others, not himself.
(2) The family of the kingdom of God takes precedence over human families. Jesus had at least four brothers whom he might have asked to take on this responsibility, but instead he gave it to a “brother” in the kingdom.
To explore this episode a little further, one fascinating and beautiful aspect of the account of Jesus’ crucifixion in John’s gospel is the way it’s arranged as a seven-part chiasm:
A: Jesus is Brought to the Place of Execution
B: Pilate Refuses the Jewish Leaders’ Request to Change the Inscription
C: The Soldiers At the Cross Cast Lots for Jesus’ Clothes
D: Jesus Entrusts Mary into John’s Care
C: The Soldiers At the Cross Give Jesus Wine to Drink
B: Pilate Grants the Jewish Leaders’ Request to Break the Legs of the Crucified Prisoners
A: Jesus is Taken from the Place of Execution
As I note in my study guide to the gospel of John, the central placement within this arrangement of the episode in which Jesus entrusts Mary to John’s care “shows that Jesus was a person of compassion who extended mercy and care to others right to the very end of his life.”
“But,” I also observe, “it’s interesting that an account of the crucifixion would not have Jesus’ actual death at its center. John may have an additional purpose for including this episode and placing it where he does. He may be putting his central focus on the effects of Jesus’ death. John may be portraying how Jesus’ death is for ‘the scattered children of God, to bring them together and make them one.’ Through his death, believers in Jesus become part of a new family, which is their true family.”
I then ask in the guide: “Are there some other followers of Jesus who are ‘just like family’ to you? What creates the bond between you?”
What would you say?