Was it where she had been that really made you all surprised

你的句子改写成非强调句是：
Where she had been really made us all surprised.
所以,where是主语从句的连接词,同时也是主语从句的地点状语.
再问： 那been的表语呢？
再答： 你好。你的句子里没有表语，只有地点状语where.--------如果把where具体化，就是： That she had been in the forest alone surprised us all.--------看见了吗，in the forest 就是地点状语。