The correct answer is $\boxed{\text{C.}}$
To solve this question, we need to understand the meaning of each relationship symbol.
- $A $ B means A is the brother of B.
- $A @ B means A is the wife of B.
- $A # B means A is the daughter of B.
- $A * B means A is the father of B.
Given this information, we can eliminate options A and B immediately. In option A, $U$ is the father of $W$, but there is no indication that $W$ is the wife of $P$. In option B, $U$ is the father of $Q$, but there is no indication that $Q$ is the daughter of $P$.
In option C, $U$ is the father of $T$, and $T$ is the wife of $P$. This satisfies the condition that $U$ is the father-in-law of $P$.
In option D, $U$ is the father of $T$, and $T$ is the daughter of $W$. This does not satisfy the condition that $U$ is the father-in-law of $P$.
Therefore, the correct answer is $\boxed{\text{C.}}$