Will the husband be sinful if he applies the Hanbali opinion and takes his wife back without her consent or the consent of her family? What is the ruling if her family applies the opinion of the majority and does not accept her return? And who has the greater right to apply one of the two opinions in this case?

There is no harm in acting upon the opinion of some scholars when there is a difference of opinion, as long as the Muslim is confident in its correctness. If the spouses agree to adopt the opinion of the Hanbalis on a certain issue, believing it to be the truth, then there is no sin upon them, and the wife's family has no right to prevent her from returning to her husband. However, if a dispute arises between the spouses or with her family, the Sharia judge is the one who resolves the dispute, because a judge's ruling removes disagreement. But, if the wife believes the divorce to be irrevocable, it is not permissible for her to return to her husband. It is stated in "Mawahib al-Jalil" that if the wife chooses herself (in a divorce scenario) believing that she has three options, while the husband considers it one (irrevocable divorce), it is not permissible for her to allow him to have conjugal relations with her. And even if a judge rules that the option is a single revocable divorce and the husband takes her back, this is not permissible for her as long as she considers it unlawful, and it is not permissible for him to approach her except if she is unwilling.