They decided to stay long enough to eat her food and use her bathhouse.
Also have to remind people that these dark elves are not Drows. In my little fantasy universe, unless they're actual warriors, they're not much good in a fight. They're more like social butterflies who has power thanks to money and status, so the amazon and shieldmaiden don't have to worry about being unarmed. The dark elf lady would hardy be able to lift up their weapons, let alone know how to use them.