A:
If the person
breaks his Sawm (Fast) during Ramadan for a legal excuse then fails to make up for it without negligence on his part then dies, there is no blame on him. But if he delays making up for the missed days without a legal excuse and then dies, it is permissible for any of his relatives to observe Sawm on his behalf as it is authentically reported that the Prophet (peace be upon him) said:
If anyone dies in a state (that he had to complete) some days of fast, his heir must fast on his behalf.
Reported by Al-Bukhari and Muslim.