Can you explain why you didn’t stay in home as directed?

这是一个省略了 was  的“比较状语从句”。等于：as was directed。这里 as  作从句的主语，指代主句中肯定意义的谓语部分（stay in home）。这种省略，从结构上一般是不能补充完整的，你可以从句意上理解即可。

as + （is）+ 过去分词  省略结构：

用于此句式的动词，一般是表示“计划，想象，预料，叙述，描述，提及，说及，显示，指出”之类的动词，多用于议论文体。常见的有：

as planned 正如计划的那样

as scheduled 正如安排的那样

as expected 正如预料的那样

as imagined 正如想象的那样

as arranged 正如安排的那样

as seen from above 正如从上述看的那样

as told before 正如前述

as shown above 正如上面显示的那样

as said 正如说过的（那样）

as mentioned 正如提到的（那样）

as described 正如描述的（那样）

as discussed 正如讨论过的（那样）

as noted 正如叙述到的（那样）

as stated 正如说指出的（那样）

as announced 正如宣布的（那样）

as pointed out 正如已经指出的（那样）

as indicated 如前所示（那样）

as hinted 正如已经暗示的（那样）

as told 正如已经告知的（那样）

as shown above 如上显示（那样）

as emphasized 正如已经强调的（那样）

as observed 正如已观察到的（那样）

as explained 正如已经解释过的（那样）

as suggested 正如已经提出的（那样）

as depicted in the picture  如图所示