Well, in this particular case, not fighting IS putting the kid into danger, since a defeated order would mean both H and her kid get to be Hel's brand new toy/slaves, and a cleric of Hylgia's power will be invaluable in this battle.
She doesn't know about the dwarfpocalypse, though (Roy just talked about some random end-of-world threat, but that kind of generic menace is just "another day at the office" for a high-level adventurer), so it doesn't really excuses her lack of common sense. But it's kinda ironic she is actually protecting her child while making an horrendously wrong decision. ^^