Alexander Whyte in his Bible characters book describes Nicodemus as visiting Jesus at Mary and Martha's house - is there a reason to believe this is so?
According to Jn 3 there is no reference as to where this discussion took place. It could have been anywhere, inside or out. There may be some apocryphal tradition that it took place in Mary and Martha's house but that is all it is.
I think the assumption is that Jesus made it his custom to visit the home of Mary and Martha (& Lazarus) when visiting Jerusalem. I think that Alexander Whyte has used some license to state as fact what may be implied as possibility.