Mary might have giggled because she was in a lighthearted mood. It could also be that a hidden surprise was revealed at the end, causing her to react that way. Or maybe it was just a way for the author to show her positive emotions without giving a clear explanation.
It ends when the main conflict is resolved and all loose ends are tied up. That's just how most stories work.
It's hard to say exactly. Maybe in a particular context or story, 30 has been assigned a symbolic meaning representing the conclusion.
Maybe it's to create a big shock and leave a lasting impression on the readers.
It usually ends when the main conflict is resolved and the characters' arcs reach a satisfying conclusion.
I think Mary Shelley included Justine's back story to evoke empathy from the readers. It makes Justine's situation more relatable and adds a layer of tragedy to the story. Additionally, it could be a way to explore themes such as injustice and morality.
Maybe Mary Christmas had some bad traits or did something wrong that made people dislike her.
It could be that Krakauer wants to give readers a sense of conclusion and then build up the story to explain how it got there. This approach can make the journey more intriguing.
It might be that her appearance at the end is to show character growth or to offer a sense of closure. Maybe she has some important information or message to convey.
It could be a symbol of ultimate destruction and chaos, emphasizing the dystopian nature of the setting.
It could be due to his mental state and the stress of the events. Lennie's mind was already fragile, and the culmination of everything might have pushed him over the edge, causing hallucinations.