Let the two-digit number be \( 10a + b \), where \( a \) is the tens digit and \( b \) is the ones digit.
From condition I: The number is a multiple of 62, so we check the multiples of 62 within the two-digit range:
\[
62 \times 1 = 62 \quad \text{(valid two-digit number)}
\]
\[
62 \times 2 = 124 \quad \text{(not a valid two-digit number)}
\]
So, the number must be 62.
From condition II: \( a + b = 9 \), where \( a = 6 \) and \( b = 2 \). Thus, \( 6 + 2 = 9 \), which satisfies the condition.
Therefore, the two-digit number is \( 62 \).
Thus, the correct answer is \( \boxed{1} \).