Without getting any closer than he needs to, Piedra will move into a position where he can see into the barn.
Assuming that it appears clear, he will creep upto the barn and have a proper look. Likewise the house.
Only, if he a completely sure that there is nobody waiting in ambush (that is to say he has visually checked all parts of the house and barn, including checking the floor for trap doors) will he signal for Sam and Tevye to come in. If this means that he needs to enter the house then so be it.