Is a father who passed away while in a coma on Saturday, 3rd of Sha’ban—and who had intended to fast the entirety of Sha’ban—considered to have completed the fast of that day, even though he did not fast on that day due to his coma?

The Sunnah indicates that whatever a sick person used to do in good health is recorded for him, based on the hadith: "When a servant falls ill or travels, what he used to do when he was a resident and healthy is recorded for him." It is hoped that the reward for fasting the days of Sha'ban that your father did not fast will be recorded for him, as long as he used to fast them previously.