None of them are quite right. I'm going to graduate in May. I'm going to graduate this May. I'm graduating this May. I'm graduating in May. I'm hopefully graduating in May. I'm hopefully graduating this May. * Note: this use of "hopefully" is technically not correct. However, it is used so often that it is no longer really out of place. More proper grammar would be "I am hopeful that I will graduate in May." Hopefully is an adverb. As written, it modifies "graduating," meaning that you are graduating with hope. What you are really trying to say is that you are making the statement with hope that it is true. People misuse this often enough that most people will not even think it sounds strange.

I'm going to graduate in May. or I'm going to graduate this May. or Hopefully I'm graduating this May. or Hopefully I will graduate by this May.

I'm going to graduate in May. or I'm going to graduate this May. or Hopefully I'm graduating this May. or Hopefully I will graduate by this May.

I'm going to graduate in this May. correct