My duty as a hero is already over.
Sarah, it is your business to take care of visitors, right?
Unfortunately, I wasn't able to fulfill my duty.
If you have an eye for service, then you always think helping people is your duty! If you see it, then you offer your service. It's the right thing to do!
This word consists of the on'yomi reading for 役 and the kun'yomi reading for 目. You've learned them both so you should be able to read this word too!