Yeah, we're never too old to support each other and need support sometimes.
As well as everyone else pointing out that it's an adventurer party, Fern herself is no slouch. With just a cold, no reason to think she couldn't conjure up something in a pinch to deal with a random civilian. And it's a place Frieren had been before albeit a long time ago.@TetraSky
Did they seriously leave a vulnerable girl in the house of a random stranger? All alone with said stranger? How trusting...