Hi Anupama,
Mock simulator would be a great way to test your preparation. If you haven't taken yet, you should take it ASAP. It will also prepare you to sit for long hours and focus on test. I believe you will be able to make a decision then.
Questions on examination are mostly agile (more than 70%)
I found Rita Mulchay's book difficult but as I bought it, read all the chapters and completed the quizzes. I read this book once and I was done with it.
I would suggest you to read the following for Agile:
1. Agile practice guide
2. Scrum guides 2017, 2020