Certainly, I think she was loyal to them from season 1 and onwards, she might have talked a more shallow game but she never let anyone know about them (sure people might have thought she was crazy if she had but I still think she deserves credit for being initiated into this knowledge of the dark side and stepping up to the plate to be part of it rather than run and hide), she was there when they needed help (what limited help she could give) and even though she snarked at them sometimes I don't feel it was from a place of true dislike, it was just who she was - blunt - but a teenager so it came out harsh at times.
So I would certainly say that she was loyal.