A newly widowed young-ish woman receives a thoughtful letter from her close friend about her dearly departed husband and cash falls out of it. This is not a teenager's birthday card from a well-meaning but emotionally unavailable grandpa. This is an adult woman who, higher education notwithstanding, wants to maintain her dignity after her husband's death.
Instead of traditional goodbyes that interrupt the couple's enjoyment, quietly slipping out of a wedding reception allows the newlyweds to appreciate their expensive party.
As a person who moved to the US, it's baffling to see people stroll around their homes in sneakers or even boots! I can't help but think about all the dirt, germs, and unidentified outside substances that must be getting tracked all over their floors.
You cannot reasonably be expected to receive uninvited guests particularly after a recent move so there is nothing wrong with accepting the oranges and saying, 'We look forward to being able to have you over when we are unpacked and ready for guests.' Miss Manners is only relieved that your neighbor also had the good manners and situational awareness to leave after 10 minutes.