Answer
(Fatwa: 474/474/M=1431)
Halalah is required in case of marrying previous husband who has given three talaqs. If khula has taken place only once between husband and wife, and wife wants to come into the nikah of previous husband again, in this case there is no need of halalah. In the presence of legal witnesses both of you can remarry with mutual consent, and it is better to do so with the permission and consent of parents.
Yes, if any talaq also had taken place before Khula and by occurring khula, the total number of talaqs were talaqs or husband gave three talaqs during khula, then ask the question again by explaining it.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband