I literally got stuck of the explanation of Quotient map in the book Topology by Munkres when it comes to the explanation using Saturation.
Can anyone please refer another book where I can get a explanation (using Saturation), and explained easily!!
I got stuck since the book says this:
It says $C$ is complete inverse image of $Y$. $\color{red}{\text{Then $C=X$ isn't! What am I missing here}}$.

I read through the whole Chapter on 'The Quotient Topology' in Munkres and understood absolutely nothing, it was only when I read about the Quotient Topology in John Lee's Introduction to Topological Manifolds that I finally grasped the concepts. (It is a delight to read)
So with regards to your request for another book reference, I would recommend that book, which goes pretty in depth on some of the topic related to the Quotient Topology and Quotient Spaces.