There are many questions you need to answer before choosing the stack
What you need to become, A full stack developer? Or a backend developer or a front end developer?
Full Stack= you can create the complete backend and front end
Backend- You can work on server-side programming like (Java, c# Node etc)
Front end - You can create User Interface with (Java Script and Javascript Frameworks like React, Vue etc)
Now if you want to become a full stack developer
Choose the right stack it can be .net along with angular or react or vue
or meanstack -Mongo db, expressjs and Node
There are other server side languages like Python, ruby etc. Python is easy to learn but ideal for AI, ML type of stuff.
Now identify yourself. This cannot be achieved in a day, it should be a mission it may take years to become a proficient developer.
PS: Whatsoever you have to learn HTML and CSS to start with if you deal with front end.
Also stick on to one stack. Dont be jack of all. be a master of one.