Questions & Answers about Вам больше ничего не нужно?
Because нужно normally goes with the dative case to show who something is necessary for.
So вам literally means to you / for you, not you as a subject.
Russian often says things like:
- Мне нужно — I need
- Тебе нужно — you need, informal
- Вам нужно — you need, polite or plural
So the structure is not like English you need.... It is closer to for you, it is necessary....
Here больше means any more, anything else, or further depending on the context.
It does not literally mean only bigger here. Compare:
- Мне больше не нужно — I don’t need any more
- Вам больше ничего не нужно? — You don’t need anything else?
So больше adds the idea of additional or further need.