Everything he （had been taken） away from him before he retur

错了
应该是Everything he had
had been taken away from him .
Everything (he had), he had 充当的定语从句修饰everything,他所拥有的所有的东西.
我第二行写的 had been taken 是因为在before 前面并且before后的returned是过去式,这个需要用过去完成时,而且是被动语态.
故而括号内的应该是 had had been taken
此外,本句话的意思是：
在他回家之前,所有的东西都被剥夺掉了（类似的意思嘛）.