Assuming that most people had to come from far away, and horse-drawn carriages weren't the fastest, how did people leave at the end of the night? Did hosts have to provide everyone with somewhere to sleep, too? And how late did parties normally last?
EDIT: Anyone can post for their area of expertise, but I was picturing the 17th-19th century England or Western Europe.
What period and country are you asking about? There’s no context in your question.
Balls usually started in the evening (usually between six and nine) and had a wide range of durations. One nineteenth-century ball went until 7am the next day. But the majority were a few hours long.
At the end of the ball, the guests always departed. People left in ways that would be broadly familiar to us today, only without automobiles. Some brought their own carriages. Their drivers would wait outside, often in a small structure set aside for them. (As one Frenchman noted with dry wit, this was the most important room for a ball: otherwise, the drivers would freeze to death in winter and they would all be trapped together. Having a low opinion of the aristocracy, he joked this would inevitably lead to bloodshed.)
Others rented carriages in a fashion basically similar to a taxi, which would wait for them. And some people rented a taxi and a team for the night, in which case it was like renting a car and driver for a single day. Likewise, taxis would often loiter nearby to pick people up. In general, people left however they arrived. There was some status jockeying here, as there is today. Coming in a finely appointed fully owned coach with servants and your own team of horses signaled wealth. Coming by taxi signaled (relative) lack of resources. And at least one 18th century teenaged daughter of a wealthy gentleman bothered her father to let her take the good carriage so she wouldn't be embarrassed in front of her friends and the boys.