--Mum its late. Why are you still here?--Dad hasnt come back yet. I for him.A. am waiti

问题补充：

--Mum, its late. Why are you still here?

--Dad hasn come back yet. I for him.

A. am waiting B. was waiting C. waited

答案：

解析：句意：妈妈，太晚了。你为什么还在这儿？——爸爸还没有回来。我正在等他。结合语境可知下文描述的是说话时正在进行的动作，故用现在进行时态，选A。