I'm the same as wonderwiper.....the only time I wear socks is to go outside in the winter. I can not stand to have socks on and I have hot feet so I think that's why. The odd time I will wear slippers in the house but that is only in Fall/Winter.
I am a fan of choosing my battles and for me, this isn't one I would worry about until it was time to go outside. However, if it's something you are firm on than be consistent and eventually she will realize that it's a daycare rule and socks have to be on. I agree that home and daycare have different rules so what they do at home doesn't matter....do what you need to do at dc. Will she wear slippers instead of socks?