If A $ B means B is the father of A; A # B means B is the mother of A; A * B means B is the sister of A and A @ B means B is the husband of A, which of the following indicates that N is the grandmother of P?

The correct answer is $\boxed{\text{C. P # Q $ N * M}}$.

Here is a brief explanation of each option:

• Option A: $P * Q # M $ N$ means $P$ is the sister of $Q$, who is the mother of $M$. This does not indicate that $N$ is the grandmother of $P$.
• Option B: $P @ Q $ M # N$ means $P$ is the husband of $Q$, who is the mother of $M$. This does not indicate that $N$ is the grandmother of $P$.
• Option C: $P # Q $ N * M$ means $P$ is the mother of $Q$, who is the daughter of $N$. This indicates that $N$ is the grandmother of $P$.
• Option D: None of these options indicates that $N$ is the grandmother of $P$.