Ruling on wiping over short socks, if he pulled them up above the ankles and wiped over them, then they slipped below the ankles
Question

What is the ruling on wearing socks that are somewhat short if they were put on after doing wudu’, then when doing wudu’ again, I pull them up so that they cover the ankles and wipe over them?
Praise be to Allah.Firstly:
What is stipulated in order for it to be permissible to wipe over the socks
It is permissible to wipe over the khuffs and socks subject to certain conditions, one of which is that the socks must cover the place that must be washed when doing wudu. In other words, the socks must cover the feet and ankles, and it is not permissible to wipe over socks which come below the ankles.
The majority of scholars disallowed wiping over socks, but the Hanbalis permitted it if the conditions regarding the khuffs are met, one of which is that they must cover the ankles.
Ibn Qudamah (may Allah have mercy on him) said in al-Mughni (1/214): It is not permissible to wipe over anything except the khuffs and anything that takes their place that is cut down, and the like, that comes above the ankles.
What this means – and Allah knows best – is that the ruling on the khuffs also applies to that which takes the place of the khuffs and covers what must be washed when doing wudu, if it is possible to walk in it and it stays put by itself. That which has been cut down is the short khuff; it is only permissible to wipe over it if it covers the place that must be washed and the ankles cannot be seen, because it is tight or wrapped. This is the view of al-Shafa‘i and Abu Thawr.
But if it is cut so short that it comes below the ankles, it is not permissible to wipe over it. This is the correct view, narrated from Malik. It was narrated from him and from al-Awza‘i that it is permissible to wipe over it. End quote.
It says in Kashshaf al-Qina‘ (1/115): It is not valid to wipe over anything except that which covers the area that must be washed, which is the entire foot, otherwise it would mean that what is covered is to be wiped and what is not covered is to be washed, and there is no way to do both; therefore the entire foot [including the ankles] must be washed, because that is the basic principle. End quote.
Ibn Hazm disagreed, and said that it is permissible to wipe over [the khuff] that comes below the ankles.
Please see the answer to question no. 176866 .
Secondly:
The ruling on socks that slip below the ankles after being wiped over
If you wiped over the socks when they were covering the ankles, it is valid to wipe over them. But if they slipped down below the ankles after that, doing wudu by wiping over them is not valid and your current wudu is invalidated according to the Hanbalis, who say that it is permissible to wipe over the socks.
What is meant by it not being valid to do wudu by wiping over them is that it is not permissible for you to wipe over them again, until after you have done wudu in full, which includes washing your feet.
Some of the scholars are of the view that you cannot do wudu again by wiping over the socks, but the current wudu that you did before the socks slipped down below the ankles is still valid.
It says in Zad al-Ma‘ad: If any part of the place that must be washed becomes exposed after wudu was invalidated or the period during which wiping over the socks is allowed expires, then the individual must do wudu all over again [which includes washing the feet].
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) favoured the view that wudu is not invalidated [if the khuffs or socks slip below the ankle), and this was regarded as more likely to be correct by Shaykh Ibn ‘Uthaymin. See: ash-Sharh al-Mumti‘ (1/264).
If you can no longer wipe over your socks when you do wudu because the socks have slipped below the ankles, then you will not be able to avail yourself of this concession which allows wiping over the socks. Based on that, if you want to avail yourself of this concession, then you should choose long socks that cover the ankles and will stay up, and will not drop down to the part that must be washed when doing wudu.
And Allah knows best.