What is the ruling regarding the 'Umrahs of one who, out of ignorance, omitted the Farewell Tawaf and Sa'i for Hajj, then performed them after completing the 'Umrahs? And did the Tawaf and Sa'i of 'Umrah suffice for the Tawaf and Sa'i of Hajj?

The circumambulation of Ifadah (Tawaf al-Ifadah) and the ritual walk (Sa'i) of Hajj are two pillars without which Hajj is incomplete. Whoever omits them remains forbidden from women until they perform them. It is obligatory for them to return to Mecca to perform them, no matter how long it takes. If one performs Umrah after their Hajj, then the circumambulation and ritual walk of their first Umrah after Hajj will suffice for the circumambulation and ritual walk of Hajj, because their ihram for Umrah is considered invalid. The questioner is obligated to offer a sheep to be slaughtered and distributed among the poor of Mecca for having omitted the farewell circumambulation (Tawaf al-Wada') before the completion of the rituals. One should beware of obsessive doubts (waswasah) and turn away from them.