It is possible that the child isn't needing a long nap. If things stay the same is it ok with you? The reason I ask is because I doubt things will change. She isn't likely going to nap any longer no matter what you do. If it is not ok with you I would talk to mom, tell her that this child isn't sleeping as long as she needs therefore not adjusting to the daycare routine as she needs to. Tell mom it is disruptive to others when she wakes early and give her a timeline in order for it to get better (although I doubt it will). So for example tell mom that you will give it until January 15th to reassess the issue. Once Jan 15th comes if the issue hasn't changed then give your 2 weeks notice. If you aren't willing to terminate I would say you need to accept that this child isn't going to sleep for longer than an hour.