Who? Head Maid? I reckon the danger Maou will be facing is personality contamination. She's probably conversing with her predecessors in the tomb. Maybe she needs to convince them that rather than wage war against humans, it's better to try to live in peace. It might not be an easy task (they are supposed to be demons) and they might try to convince her otherwise instead. In light of everything we have seen, there must be something special about being Maou, something that brute force can't necessarily replace. Maybe it's the ability to deal with the earlier Maous.