1) # 4 is the way to go for starters. Wouldn’t you use a different block to walk down if you felt threatened by the people living there, even if it wasn’t the most convinient way?
2)Ask your LOR
3) A possible solution with pwermission from the LOR. Why can’t yur wife very directly tell him, that as the manager of the store he has the right to say hello, can I help you, respond tp your questions or concerns, however, all other questions and conversations are off limits due to Tznius reasons. I am sure that he will stop with your wife immediately, and possibly get him thinking about others.