if this was DC1, the answer would be nothing, as she is too young to care or even notice, but her older sister will expect the baby to receive presents too. In our house FC only brings small cheap things, and there aren't many suitable for small babies.
So far she has got Christmas bibs, socks, a teething toy, a cuddly reindeer, a hairbrush and a bath toy. My other ideas are a book, a rattle type toy, baby wipes that are at least useful, bubble bath for when she is older. Any other suggestions welcome!