Is the Farewell Tawaf valid for a woman whose menstruation stopped for 8 hours due to taking pills, then she performed Tawaf, then her menstruation returned, and what should she do if it is not valid?

The period of purity interrupting menstruation is a valid state of purity. So, if your wife observes purity by one of its two signs (dryness or the white discharge) and then performs ghusl and circumambulates for the Ifadah (Tawaf al-Ifadah), her circumambulation is valid, even if the bleeding returns afterward.