If they are breaking the rules and making the game un-enjoyable, then report them. If they are just being rude, well, wish their soul the healing they need and move on. People don't become bitter and mean for no reason.
Ignore them if that helps you feel better, or take the bait and get into an argument if you think you need to stand up for yourself. But careful, you can't easily step into their realm and vibration without getting dirty yourself.
Let it go if it's trivial. Carrying a grudge and being mean and spiteful just continues to lead one further down the road into becoming a version of themselves they may just hate and despise the most.