Concept:
The Rag-Ragini system has different opinions or Mats.
Different musicologists classified ragas and raginis in different numbers.
Step 1: Check Assertion (A).
The assertion states that Hanumanmat describes:
\[
6 \text{ raag and } 36 \text{ raginis}
\]
and Someshwar Mat describes:
\[
6 \text{ raag and } 30 \text{ raginis}
\]
This statement is correct in the given context.
Step 2: Check Reason (R).
The reason says that in the Purush ragas of Hanumanmat and Someshwar Mat, Bhairav, Shree and Megha are common.
This statement is also correct.
Step 3: Check explanation.
However, the common presence of Bhairav, Shree and Megha does not explain why one system has 36 raginis and the other has 30 raginis.
So, Reason is true, but it is not the correct explanation of Assertion.
Step 4: Final conclusion.
Both Assertion and Reason are correct, but Reason does not correctly explain Assertion.
Hence:
\[
\boxed{\text{(B)}}
\]