Answer
0.79 MeV
Work Step by Step
The rest energy of the 3 product particles is less than the rest energy of the neutron. The kinetic energy arises from the decrease in rest energy.
$$KE=m_nc^2-( m_pc^2+ m_ec^2+ m_{\nu}c^2)$$
$$KE=939.57MeV-(938.27MeV+0.511MeV+ 0)=0.79MeV$$
