It is better for a woman to wear socks even if her garment covers her feet
Question

                If a womans abiah is long enough to cover her feet does she have to wear socks?
Praise be to Allah.The Muslim woman is required to cover all of her body 
          in front of men. Hence she is allowed to let her garment drag by being 
          a cubit longer in order to cover her feet. What the woman has to do 
          is to cover her feet either by wearing a loose and long garment or by 
          wearing socks or the like. If she covers her feet then she does not 
          have to wear socks, but if she wears socks this will be more covering, 
          so it is recommended. And Allaah knows best.