Is a woman's second 'tahallul' valid if she menstruated at the 'miqat' and completed the Hajj rituals, knowing that she performed the 'Tawaf al-Ifadah' after the first 'tahallul' and did not perform 'sa'i' thereafter?

The two signs of purity are: the cessation of blood and the dryness of the locale, or the discharge of the white secretion. Whichever of them occurs first establishes purity. The spotting that returns after purity is considered menstruation, especially if it is within the usual period. Purity is a condition for the validity of circumambulation (Tawaf (definition)). If a menstruating woman performs Tawaf without purity, her Tawaf is invalid, and she must repeat the Sa'i after a valid Tawaf.