Does giving a monthly sum to the children of a man who passed away—after taking money from him without his knowledge and then repenting—expiate the sin and prevent him from being held accountable on the Day of Judgment?

The money taken must be returned to the man's heirs, bearing in mind that the heirs may not be limited to his children. By doing so, the claim for the money will be dropped on the Day of Judgment. As for atonement, it is through sincere repentance and diligent performance of good deeds, including showing kindness to the man's children who have no guardian, in fulfillment of the Almighty's saying: "But indeed, I am a perpetual forgiver of whoever repents and believes and does righteousness and then is guided." (Taha: 82).