I want to send a thank you to a local government official. getting flowers delivered is like minimum $50 these days so fuck that. something like a gift card might be inappropriate for a government employee to accept.
If their boss was being a problem, make sure you don't tell them specific details about how the employee helped. Especially if the employee bent some rules or otherwise went above what they should have. It might get the employee in trouble.
Make sure you're not getting her in trouble with her boss. Maybe her boss didn't want to help you for some reason, and she was going around her boss. Just double check with her before you say anything to her boss.