I would like to recommend this book[0]. By reading this book, you will be able to grok C. You'll learn how your C programs interact with the hardware. Learn about the stack and how it is used in calling functions. Learn about pointers and how it is represented in assembly language. Learn how arrays in C and how it is accessed in memory. And many more! I keep recommending this book because this had enlightened me in understanding how computers work and I wouldn't get tired of recommending this. If you read just half of the book, you'll gain confidence especially during coding interviews. This was my experience though. Believe me.
[0] - https://www.amazon.com/Assembly-Language-Computer-Architectu...