Who is the comedian who wirites and plays a guitar composition that he says is for a grade in college and it is a mixture of Beethoven the Beatles etc. all meshed together for the piece?

The comedian you're referring to is Bo Burnham. In his special "Make Happy," he performs a composition that humorously blends elements from various musical influences, including Beethoven and The Beatles, creating a unique and entertaining piece that showcases his musical talent alongside his comedic style.