They have a lot more experience dealing with the *emperor* than she does. Getting her way isn't worth much if she's too way inexperienced about the greater danger she's now in to be able to make an educated decision. The emperor is a much more dangerous enemy than her foster family.
I don't think this is really about experience. This is about both guys wanting her to stay with them, and them fighting about that. There are pros and cons to staying with both men, so they could literally just lay out the pros and cons and ask her to decide. They don't do this. Instead they fight with each other to try and make the decision for her. Lack of experience doesn't mean someone's own will should be disregarded.
It's already pretty obvious her decision would be to stay at her fiance's, the duke's house, though. Both the redhead and the fiance know she'd choose the fiance's place mostly out of feeling guilty for staying away from him when she's the only one who can heal him, and not because it's safer at the fiance's. She also doesn't trust the redhead with the tombstones' secret. Otherwise, she'd think of a pretty good solution, like using a decoy to pose as her while she stays at the guild and finishes visiting the tombstones (she wouldn't be able to visit them from the fiance's house undetected, since the emperor is keeping the fiance's house under surveillance). Moreover, because of her lack of experience, she makes important errors in judgement, like mistaking the hooded men who threatened her, her fiance and adoptive brother in the woods for her foster father's men, when they were actually the emperor's men (who are also keeping her fiance's house under watch) and thus a lot more dangerous... But oh well, I guess you're still right in the end. The person's own will absolutely can not be disregarded.
Ah yes, just what I love, two men making decisions for a woman and ignoring her own opinion.