Answer
67.5 MeV
Work Step by Step
The minimum kinetic energy for the process results in the 2 protons and the newly-created $\pi^o$ at rest. In that case, the initial kinetic energy equals the rest mass energy of the $\pi^o$, which is 135.0 MeV.
Each proton started with half of that kinetic energy, or 67.5 MeV.
