"In the end of the evening, nobody can leave the house."
Translation:À la fin de la soirée, personne ne peut quitter la maison.
I actually just found out why the word order is changed. If you want to use nobody as a subject, you just use "personne ne". For example, "nobody likes me" is "personne ne m'aime" but "i don't like anybody" is "je n'aime personne".
The same thing holds for "rien" btw .. so "nothing is enjoyable for me" is "ne rien me plaît" but "i don't eat anything" is "je ne mange rien".
"À fin de" doesn't exist, it's missing an article. For "en fin de", see my earlier message. However, "afin de" does exist, and it means "in order to", which is quite different from the meaning of "à la fin de". It does come from "à fin de" but be careful about the spelling, spelling it in two words in a mistake.
Because "Personne" already includes the negative, in the same way you say "Nobody can leave the house" and not "Nobody cannot leave the house". That would be a double negative, and imply that nobody is unable to leave the house (which is the opposite of what you're trying to say).
You have to use "soirée" rather than "soir" here because here we're talking about the duration of the evening. Hence, since "soirée" is female it's "de la" rather than "du" (male). If we were just talking about a point in time, e.g., making an appointment for some evening next week, we'd use "soir".