After listening to her niece's story, Kwon Yoori understands her dire situation. She appreciates that her niece came to warn her about the keepers. Staying at the inn is not safe. The stable boy is brain dead. The inn owner has sent words to the boy's family. The timekeeper organization will find out soon.
"Pretend to be my brother," She tells her niece. "We will leave tomorrow."
To be honest, her niece is too pretty and feminine to act like a man. Yoori is afraid that her niece will attract men who like feminine men with her beauty. The other problem is that her niece has no idea about her pretty face. She is also wounded. Still, it's better to pretend to be a man than a woman in this era. She already attracted Li Jun's attention in the original timeline and ended up marrying him because of the emperor's decree.