Bismillahi Al-Rahmani Al-Rahim

Mixing Madhhabs

If a shafi or hanafi took a rukhsa (legal dispensation) from the hanbali school i.e wiping over modern socks, would his salat be valid although he did wudu according to the hanbalies?

It is best to refer this question directly to the Hanafi or Shafi`i groups, especially since the madhhabs have slightly different conditions for validly mixing madhhabs. It is most likely that according to both maddhabs the payer will be invalid because the person has not fulfilled the condition of ablution in their own madhhab (because of the socks), and since ablution is a condition for the prayer's validity it must be taken into account.

This is a general answer, and specific cases are likely to have specific answers.

And Allah knows best.

wa al-salamu `alaykum