Is a husband entitled to prevent his wife from making up for missed Ramadan fasts until the month of Sha’ban, and if the wife then falls ill in Sha’ban and is unable to make them up, does the sin fall upon her or upon the husband?

The time for making up missed Ramadan fasts extends until Sha'ban, based on the hadith of Aisha (may Allah be pleased with her) that her making up was in Sha'ban. It is safer to hasten in making up the fasts. If one is unable to make up the fasts in Sha'ban due to illness, then they should make them up after the following Ramadan. There is no sin upon her or upon the husband, and there is no expiatory feeding required from them.