After playing _________ hours of tennis, I am feeling _________ tired to walk back.

The correct option is Two/too.

Let us break down the sentence step-by-step to understand why this option is correct:

1. Analyzing the first blank: "After playing _________ hours of tennis..."
Here, we need a word to specify the number or quantity of hours played. The word "Two" is a numeral representing the number 2. Placing "Two" in the first blank makes grammatical sense, indicating a specific duration: "After playing two hours of tennis..."

2. Analyzing the second blank: "...I am feeling _________ tired to walk back."
Here, we need an adverb that modifies the adjective "tired" to indicate an excessive degree, leading to a certain result (being unable to walk back). The word "too" is an adverb that means "excessively" or "to a higher degree than is desirable." The structure "too [adjective] to [verb]" is a standard English grammatical construction used to indicate that a condition is so extreme that a subsequent action is impossible. Placing "too" in the second blank fits perfectly: "...I am feeling too tired to walk back."

Therefore, combining the two correct words gives us "Two/too", which correctly completes the sentence: "After playing two hours of tennis, I am feeling too tired to walk back."