Suppose this, if there are advanced civilisations doing interstellar travel and there really is a 200km object that could hit Earth (I understand this is too far out), what would be the way to ask them for help?
The probability of a starship being within 5 lightyears of earth is likely zero. If there is one, it's probably because it's already on its way here.
There is also a possibility that there are advanced civilizations that jailbreaked the Universe/Reality and can be anywhere in seconds. Whether they give a shit about primitive civilizations like us who invented decent computers only like fifty years back is a different question altogether.
https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_e...