Yue Xuexia had brought the cubs back home while the others were allowed to stay over as well. However, because the Holy Witch and the Qin Ancestor were meditating, Elder Susan, Su Gin'er and Princess Qin Yaoyun decided to stay in the forest to protect them. This is actually the real reason why the Moon Goddess had allowed them to stay.
She can't just throw out two who are on the verge of enlightenment. Domain is important for Huashen Realm cultivators. Only by having one will allow this cultivator to have a chance to reach the next realm Void Refining (Mahayana) Realm. She had already seen the path to the next realm. The only reason she is not breaking through is because it gave her a bad feeling. This feeling of something going out of her control. That's why she is holding back with her breakthrough.
