Step 1: Understanding the Concept:
The question asks for the subject matter of a specific section, Section 9, of the Hindu Marriage Act, 1955. This Act codifies the law relating to marriage among Hindus and provides for various matrimonial remedies.
Step 2: Detailed Explanation:
Let's look at the key sections dealing with matrimonial remedies in the Hindu Marriage Act:
\begin{itemize}
\item Section 9: This section is titled "Restitution of conjugal rights." It provides a remedy to a spouse who has been deserted by the other. It states that when either the husband or the wife has, without reasonable excuse, withdrawn from the society of the other, the aggrieved party may apply for a decree for restitution of conjugal rights.
\item Section 10: Deals with Judicial Separation.
\item Section 11: Deals with Void Marriages.
\item Section 12: Deals with Voidable Marriages.
\item Section 13: Lays down the Grounds for Divorce.
\end{itemize}
Therefore, Section 9 specifically deals with the restitution of conjugal rights.
Step 3: Final Answer:
Section 9 of the Hindu Marriage Act, 1955 deals with Restitution of Conjugal Rights.