Considering how many hints she has given, how many wierd things she has done, how many times she revelead to know things that she shouldn't know if she wasn't the woman who died in a fire, i wouldn't be surprised of he thoughts of her as the same person...
The credit cards password is his birthday? Holy ****, that is grandma who doesn't use internet and hasn't moved with the times level of password difficulty. Again another thing that shows how dumb the MC actually is.