Can the Light transform an ego into an authentic-self? Or must the ego be annihilated in the process?

The ego is something the "authentic self" is doing. Unfortunately, it keeps us from being clearly aware of that self. To really see your own nature, you have to get over the biases of ego. My mother used to get all tensed up from the effort to relax. Trying to use ego to realize your self-nature is like that.