王老师从楼上下来了。

upstairs answer is right. in Chinese, we put a sentence in the pattern: sb be/do sth, that is subject+predicate+object. in this sentence, 王老师 is the subject，从楼上 is the adverbial， 下来is the predicate. we say it 王老师从楼上下来。

"樓上下來了王老師" 主題在於 王老師之所從來 其結構跟以下例句相同 也是可以成立的 1 眼前飄來了一陣霧 2 半路殺出了一個程咬金 3 後面追來了一隻狗 4 ...

It's a wrong sentence. Look at the answers below.

upstair楼上 comes 下来了Mr. Wang 王老师.