My grandfather more or less did this. My now deceased grandmother was not in a lucid state, but my grandfather submitted a ballot for her anyway. I thought about reporting him, but I doubt anything would come of it since she was alive at the time the election was held. He lives in North Carolina, which makes it worse.
The thing that really made me angry though is that my Grandmother, were she of sound mind, would NEVER approve of a man like Trump for president. She would have been disgusted by him.