(Hope this is the right forum for this)
If you could ask an alien being any question what would that question be? A few things that I would think of would be what was the nearest planets to Earth that have life on them, then the nearest with complex life, and the nearest ones with intelligent life.

Getting answers to any of these questions though may be unlikely and even if they were answered can we believe the aliens have answered them truthfully? Still it never hurts to ask.