Fill in the blank with a suitable Article if necessary :

I don't think ________ mother is home yet.

zero article

The correct answer is OPTION 4 - zero article
When we refer to close family members like mother, father, brother, etc., in a general or personal sense, no article is used.

Here, “I don't think mother is home yet” refers to one's own mother in an informal/personal context, so zero article is correct.

• “a/an mother” → incorrect (mother is specific, not general countable usage here)

• “the mother” → would imply a specific mother in a formal or defined context

The complete sentence would be: "I don't think mother is home yet."