What fallacy is this that person 1 made

Person 1: how does God show himself to people who don't know he exist

Person 2: the same way he showed to Adam and Eve

Person 1: Adam and eve aren't real therefore you're wrong

None. Person 1 asks a question, and not a claim. 

P2 Makes a Reification Fallacy by claiming that the story of Adam and Eve is a reliable account of divine revelation rather than a myth.

P1 argues that Adam and Eve are fictional and therefore P2 is wrong. This is a non-sequitur. A God could conceivably reveal itself even if Adam and Eve are fictional. So one does not necessarily follow the other.

Person 1 didn't commit any fallacy. The Adam and Eve along with the whole creation fairy tale has been disproved by biology, so God could not have possibly shown himself to them because Adam and Eve didn't ever exist.
Person 2 on the other hand with his answer has committed a few:
unfalsifiability, appeal to heaven (kind of), amazing familiarity 

EDIT (copied from my discussion with Whimsicott):
Just because something is presented in a fictional story, doesn't necessarily mean that it hasn't been replicated in real life. So, I think the argument "It was presented in fiction, therefore doesn't exist" is non sequitur . 

So, I think the argument of person 1 is a non sequitur if we want to be pedantic, but at the same time it is a response to what is implied, due to the implicit rules of language and how we introduce and extract meaning by what we DON'T say or what we say in place of something else.

Person 1: how does God show himself to people who don't know he exist 

Begs the question that a) god exists and b) god shows himself. However, this wouldn't be fallacious if person #1 and #2 have agreed for the sake of the argument to assume a+b are the case.

Some gods do show themselves. Gods such as Thor or Loki. So Person 1 must first provide an intelligible definition of the particular god which is the subject of the discussion. So, as I see it, you are stuck at this level of discussion until Person 1 provides the foundation.

Before we can discuss whether something exists, we need to know what “it” is. We need a specific definition to make sure we are all talking about the same thing. In the current discussion, I understand you to be making the proposition: God exists.

In logic, as in law, the proponent of a proposition must present (1) an intelligible definition of the god and then (2) bear the burden to adduce evidence to support its existence. No one has ever presented me with (1), so we never got to (2). 

By “intelligible definition,” I mean to state or describe (with sufficient specificity to be clearly understood by all participants in the discussion), the properties (i.e., the attributes, qualities or features regarded as a fundamental, characteristic or inherent part) of the god under discussion, which properties are not internally contradictory, not in conflict with other properties or attributes ascribed to the god and which distinguishes the god from other gods or entities.

 Note: I understand The difference between attributes and properties is subtle. Properties describe the characteristics of an object and attributes refer to additional information of an object. Most people use these two words as synonyms, and that is acceptable to me.

The problem faced by those who profess a belief in a god is not they cannot adduce any evidence to support their belief, but they cannot even specify what it is in which they claim to believe. 

For example (to borrow from Branden), the man who claims to have faith that he will win at cards can at least define what it is in which he has faith — in the sense that he knows what he means by winning at cards. But if he claims that he has faith in a god, he cannot, in any like sense, specify what he means. He can identify his god, in effect, only as a feeling, he has faith in a feeling. But since faith is only the worship of feelings, the man who declares to have faith in a god is declaring that he has a feeling about a feeling—restated a feeling that his feeling is true. Thus, faith in an undefined god is mysticism two times over. It is an act of faith twice compounded.

I doubt the person proposing the existence of a god believes in the existence of Zeus, Thor or any of the myriad of ancient Egyptian gods. By definition, as to those gods, that person is an atheist. As Richard Dawkins says, “We are all atheists about most of the gods that societies have ever believed. Some of us just go one God further.”

Consider this analogy:

Person 1: How did you get the milk?
Person 2: I went to the store in the corner of the street.
Person 1: That store is not there. You're wrong.

Person 2 is proposing an answer and person 1 denies it. Without more context, it sounds ad hoc (not the fallacy) from both ends. If Person 2 presents evidence, like a receipt and directions, maybe the store's website, then person 1 would be committing an ad hoc rescue fallacy.