@Siddharth Kundu Thanks for reply! If my understanding is right you are are using Linux azure web app If so, You may want to know that a memory dump for that kind of set up(Custom Image, Node) via Diagnostic Tools will not be available.
Recommendation here is to configure SSH at a minimum to get what you want.
Further suggest you to refer this article on Investigating Node.js Memory Leak issue in Linux App Service might be helpful.
Let us know.