I was just wondering how to properly ask when the last bus to somewhere is.
Could you say (using Tokyo, for example)
When is the last bus to Tokyo?
東京 に 終バス は 何時ですか Tōkyō ni shū basu wa nanji desu ka?
Japanese Language Stack Exchange is a question and answer site for students, teachers, and linguists wanting to discuss the finer points of the Japanese language. It only takes a minute to sign up.
Sign up to join this community東京 に 終バス は 何時ですか
In this form に is ungrammatical here, because there is no verb whose indirect object に is marking. You could remedy this by saying 東京に行く終バス, so that に is marking the location of 行く and 東京に行く modifies 終バス.
However, for the direction of a train or bus 行き【ゆき】 is a more natural way to say this, i.e. 東京行き.
To modify 終バス, you should use の, giving 東京行きの終バス.
Also, there are many ways of saying "last bus of the day" (最終バス、終バス、終発バス、赤バス、…).
Finally, rather than asking バスは何時ですか, it is probably more natural to say バスは何時に出ますか "At what time does the bus leave?".
東京行きの最終バスは何時に出ますか? Tōkyō-yuki no saishū basu wa nanji ni demasu ka?