"for" fifty dollars is correct.

Hello again Owais, Asking questions is good!!! In this case, I would say "The plumber sent me a fifty-dollar bill." The reason why is because in English, the adjective comes first: "I am a skinny boy;" "She is a pretty woman;" "I handed her a twenty-dollar bill." In your example, the fifty-dollar characterizes the bill. It could have been any other bill, but it's a fifty-dollar bill. In this case then, the adjective tells how much dollars that bill is worth. I hope this helps. Have a great day.

Hello Owais! If you want to say that the plumber did a job for you and now he sent you a bill that you need to pay, then you would choose number 2: "The plumber sent me a bill for fifty dollars." If you are trying to tell someone that the plumber sent you money, then you would say "The plumber sent me a fifty dollar bill." "A bill of fifty dollars" is wrong regardless of what you're trying to say.