Is there an idda (waiting period) for a woman divorced for the third time? Can her husband take her back during it? And where should she spend it?

The third divorce (talaq) makes a woman irrevocably divorced (ba'inah baynunah kubra). She does not become lawful for her husband again unless she marries another man and he consummates the marriage with her, and then he divorces her or dies. The waiting period (iddah) for an irrevocably divorced woman, according to the majority of scholars, is in the marital home. However, the Hanbalis hold the view that she observes her iddah wherever she wishes. If she observes her iddah in the marital home while the husband is present, she must be in a separate, independent section with its own facilities.