what's it called when some has a fear of letting someone come to their home
There is no actual term for this, but it is most probably a social phobia also known as social anxiety disorder. This is characterized by, among other things, fear of being scrutinized or judged which may arise by people coming into your home.
Usually it's called intuition. We just have a feeling that it's not a good idea, or also known as foresight.
Common sense . We have survival instincts left over from a more wild and dangerous time in human history .