Late at night meshulochim come to collect for themselves or organizations. Do I have to open the door If I do not know the people? Its for safety issues. Also, at times women are home alone either by day or night. Its unsafe for woman not knowing the men.
For a woman that doesn’t know the person, and is home alone, there’s no obligation to open the door. She can say that her husband is out, and that the meshulach should come back when he’ll be in.
For a man, there is room to doubt how realistic safety concerns are, and one must be wary of neglecting the mitzvah of giving tzedakah to the needy. However, if one has legitimate safety concerns, there would not be any obligation of opening the door.