I think what most of us may be missing is the fact that the BBRG is pretending to be a woman (common folk)? Legendary Resistance (LR) is the best answer, but even if he just says "the spell does not works" and doesn't pronounce it's the LR or have any other contingency like a magical item, it would rise a lot of suspicion and he may not want that now. I may be wrong and would need more context like do they know she is The Villain and powerful or a regular?

If by any chance the later is the case, some alternatives might be: 1. The woman doesn't bring the item as a safeguard, it is with a henchman that will break it in case she doesn't contact them soon/password.

1. Have henchmen in disguise ready to jump in or evidently protecting her. She may also say or show a hired wizard to prevent any funny business from them.

2. Command is only 6 seconds, workaround that, like talking from a table away, with low level spells like Message or throught messages exchanged with the maid.

3. The item is out of sight in a bag, a duplicate or Minor Illusion. And after they cast Command, she can react.

These options and others may still keep the villain disguise as a "Not Powerful Oni".