What is the ruling regarding the days the deceased did not fast: must they be made up by fasting, or is expiation through feeding due, given the uncertainty as to whether he made them up?

If the father was lenient in making up two days of fasting from the previous Ramadan until the Ramadan in which he passed away, it is better for one of his children to fast on his behalf as a make-up, according to the Prophet's (peace and blessings be upon him) saying: "Whoever dies owing fasts, his guardian should fast on his behalf." If a sa' of the staple food of the land (approximately 3 kilograms) is given as charity on his behalf, that would suffice. However, if he was unable to make up the fasts before Ramadan due to illness, then there is no make-up or feeding required of him, because he did not neglect them.