When Jack first opens the door and sees his family gathered around his father, his aunt says to him, "It's all over. Your father is home." What does she mean by this?

His aunt tells Jack that his father is home for good, and will not be leaving the family again. This is meant to reassure Jack that now his father is home, he will take back much of the responsibility Jack has been burdened with in the past. It also implies that Dale has come home to find redemption for his life from his family.