How can one deal with an unwelcome guest in the home, while taking into account the ties of friendship and mutual assistance between the two families?

We believe that if the questioner is able to be good to his guest and honor him, just as he hosted his family and sister, then this is more fitting; because returning a favor is a characteristic of noble people, and the Prophet, peace and blessings be upon him, encouraged recompense for good deeds, saying: "Whoever does you a favor, then recompense him; and if you do not find what to recompense him with, then supplicate for him until you see that you have recompensed him." And if he is unable to keep him for a long time, then his dismissal should be with kindness, without expulsion or humiliation, and he should apologize to him in a good manner and try to provide suitable accommodation for him, for Allah Almighty says: "And whatever good they do, never will it be denied them."