In French, the title of this story is "L'hôte," and this word has two meanings when it is translated into English. Firstly, it means the 'guest' and relates directly to the Arab prisoner who is taken to Daru's school by Balducci and becomes his guest.
Secondly, the title of this story can also be translated as the 'host' and, in this instance, relates directly to Daru, who is forced to host the prisoner when Balducci arrives with him unexpectedly. It is this interpretation of the title which relates to Daru's conflict: he has no desire to host the prisoner and is disgusted by the crime the prisoner committed. Still, he refuses to hand him over to the police, as he explains to Balducci:
"Listen, Balducci," Daru said suddenly, "every bit of this disgusts me, and first of all your fellow here. But I won't hand him over. Fight, yes, if I have to. But not that."
It is only by letting the prisoner make his own choice (to flee or go to jail) that Daru is able to resolve this conflict.