Option 1: Allow users to freely move around your app wherever they are inside the platform.
A permanent tap bar allows users to recognise where they are on the platform. How to efficiently get to another page. And how to return back to a previous state directly without having to go through multiple steps.
It's almost like an accelerator.
Having the tap bar appear and disappear depending on the page can also stagger users and boggle the whole experience.
This also falls in line with 2 of the most common UX Heuristics:
User control and freedom
Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.
Recognition rather than recall
Minimize the user's memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
Example of an app with a prevalent tap bar:
Instagram actually does this perfectly. Since even if you click away from a child page and you try to go back to it's relevant parent it takes you directly to the child page you were.
There's many others out there (e.g facebook) especially on iOS.
As always, what is good for one app might not be good for another. Test with your users and see which interaction is the most preferred/used.