Fasting this day on her part does not suffice her for making up for the missed day of last Ramadan, since it happened to be the first day of Ramadan of the year 1404 A.H., nor does it suffice her for Ramadan (Part No. 10; Page No. 346) of the year 1404 A.H., for she fasted it while it was not proven to be one of its days, rather it is a day of doubt.
Observing Sawm on the day of doubt is not valid for Ramadan.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.