Well, the problem is that she is coming back so soon. As a general rule, she should spend more time outside of the U.S. than inside. She could get lucky and get an officer that doesn't care and the officer will just let her through without asking questions. But she should be prepared to answer the following:
1) How much time she needs.
2) Why she needs so much time.
3) Why she couldn't do what she needed to do during the last trip.
4) How she would be supporting herself for this additional time since she is not allowed to work.
5) What STRONG ties she has to her home country to ensure that she will go back.
6) What preparations she has made to go back (like a round trip ticket).
There is no guarantee, but I can tell you that the more time she asks for, the harder it will be to get an approval. She should be careful that it not look like she is working for you. The idea is that she come to visit and maybe help you a bit, not that she is basically doing a job of what a nanny would be doing because then they could see that as her taking away a potential job from a U.S. worker that you could hire as a nanny. So be careful.
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