Is it permissible to take back a divorced wife immediately after the divorce, and what is the correct action if she cannot travel without a mahram, with clarification of the 'iddah period and detailing the period available for taking her back?

If this is the first or second divorce, the husband may take his wife back immediately or before the end of her waiting period ('iddah), which begins from the time of divorce and concludes with the completion of her third menstrual cycle after the divorce, or after three months for a woman who does not menstruate, or upon a pregnant woman giving birth. A divorced woman returning from lands of disbelief may travel without a mahram out of necessity.