According to the wade- davis bill, which of these would need to happen before a former confederate state could be readmitted to the untied states

The Wade- Davis Bill was introduced after the Civil War. The goal of this bill was to help the Confederate states rejoin the Union after meeting certain requirements.

In this case, the Wade- Davis Bill wanted a majority of the population within a respective southern state to take the Ironclad oath. This oath essentially says that these individuals never supported the Confederacy in the past. This oath was supposed to prove these citizens loyalty to the United States moving forward.

Even though this is passed in Congress, it is pocket vetoed by Lincoln and never gets implemented into US society.