"That is the end."
Translation:Tio estas la fino.
It's possible to imagine a context where "Tiu estas la fino" might be possible, but generally, "Tio..." is much more likely.
Use "tiu" when you're making a choice between two or more alternatives, i.e. when you're indicating "which one". If there's a stack of books and someone asks, "Which one's yours?", you can answer "That one!" = "Tiu!"
But here, it's difficult to imagine how it could mean "That one there, that is the end". That... what, exactly?
Hope that helps.