Do Socks Have to Cover the Ankles?
Question

I did some research on the issue of wiping over the Khuffayn (2 leather socks). The four Madhhabs say that the Khuff must cover the ankle. But I came across a book by Shaykh Al-Albani in which he said that it is possible to wipe over the shoe/Khuff that does not cover the ankle; this view is contrary to scholarly consensus. I hope you can explain the matter to me.
Praise be to Allah.Conditions of wiping over the Khuff (leather socks)
The four Schools of Fiqh agreed that one of the conditions for wiping over the Khuffayn (2 leather socks) is that they should cover the area that must be washed (in Wudu) – the ankles as well as the feet. If they do not cover the ankles, then wiping over them is not valid, by analogy with Wudu. Since what appears must be washed and what is covered must be wiped over, it is not possible to combine the original rule and the alternative in one limb. (See: Sharh Mukhtasar Khalil by Al-Kharashi, 179; Hashiyat Qalyubi wa `Umayrah, 1/68; Al-Mawsu`ah Al-Fiqhiyyah, 37/264) 
Does the Khuff have to cover the ankle?
There is no scholarly consensus concerning this issue; rather there is a difference of opinion among the scholars (may Allah have mercy on them). Some of the scholars regarded it as permissible to wipe over the Khuff even if it does not cover the ankles; this is the view of Ibn Hazm and was narrated from Al-Awza`i (may Allah have mercy on them). Other scholars disallow that, as is the view of the jurists of the four Schools of Fiqh. 
It says in Al-Mughni (1/180): 
“He should not wipe except over the Khuffayn or whatever takes their place, such as those that are cut down, and the like, provided that it goes further than the ankles. What that means – and Allah knows best – is anything that takes the place of the Khuffayn in covering the place that must be washed, and in which it is possible to walk, and it is firm by itself. The one that is cut down is a short Khuff . It is only permissible to wipe over it if it covers the place that must be washed in Wudu, and does not show the ankle because it is tight or tied. This is the view of Ash-Shafi`i and Abu Thawr (may Allah have mercy on them). But if it is cut lower than the ankle, it is not permissible to wipe over it. This is the correct view narrated from Malik (may Allah have mercy on him). It was also narrated from him, and from Al-Awza`i, that it is permissible to wipe over it because it is a Khuff which one can walk with and thus it is similar to that which covers (i.e., a full Khuff). But in our view it does not cover the place that must be washed, so it is more like a slipper or sandal.” 
Ibn Hazm (may Allah have mercy on him) said: 
“If the Khuffayn are cut below the ankle, then wiping over them is permissible. This is the view of Al-Awza`i. It was also narrated from him that he said: The Muhrim (a pilgrim in a state of Ihram) may wipe over the Khuffayn that are cut beneath the ankle. Others said that they cannot be wiped over unless they come above the ankle. `Ali [i.e., Ibn Hazm] said: It was narrated in an authentic report from the Messenger of Allah (blessings and peace of Allah be upon him) that he instructed people to wipe over the Khuffayn, and that he wiped over the socks. If there had been a specific limit, he (blessings and peace of Allah be upon him) would not have omitted to mention it. So it must be the case that anything that can be called a Khuff, sock or any other footwear that covers the feet may be wiped over." (Al-Muhalla  1/336). 
The fact that the four Schools of Fih agree on a matter does not mean there is consensus on it. If the Rightly-Guided Caliphs agreed on a view is not to be regarded as consensus, then in the case of anyone of lesser standing this point is even more apt. 
It says in Mudhakkirat Usul Al-Fiqh by Shaykh Muhammad Al-Amin ibn Mukhtar Ash-Shinqiti (may Allah have mercy on him): 
“According to the majority of scholars, it is not regarded as a consensus if most of the scholars of a given era agree upon some matter. Ibn Jarir At-Tabari and Abu Bakr Ar-Rawi (may Allah have mercy on them) said: For one or two scholars to have different views does not undermine the consensus of the scholars. Ahmad (may Allah have mercy on him) agreed with this point, but the majority of scholars stated that what matters is the view of all the scholars of the Ummah, because infallibility belongs to all (when they collectively agree on an issue), not just some. The argument for the opposite view is that the view of the majority should be heeded and the view of the minority should be overlooked." (Mudhakkirat Usul Al-Fiqh, 1/156) 
It also says:
“The agreement of the four caliphs does not constitute consensus according to the majority (of the scholars). The correct view is that it constitutes evidence, not consensus, because consensus can only occur if all are agreed.” 
For more details, please see this category: Wiping over the socks.
And Allah knows best.