Answer
We have $Q=\Delta mc^{2}$
For a beta decay,
$A_{p}=A_{d}+e_{-1}$,
$M_{D}=m_{d}+m_{e}$ & $M_{p}=m_{p}$
Here, $\Delta m=m_{p}-m_{d}-m_{e}$
So, $Q=\Delta mc^{2}=(m_{p}-m_{d}-m_{e})c^{2}=(m_{p}-(m_{d}+m_{e}))c^{2}=(M_{p}-M_{D})c^{2}$
Hence, proved.
Work Step by Step
We have $Q=\Delta mc^{2}$
For a beta decay,
$A_{p}=A_{d}+e_{-1}$,
$M_{D}=m_{d}+m_{e}$ & $M_{p}=m_{p}$
Here, $\Delta m=m_{p}-m_{d}-m_{e}$
So, $Q=\Delta mc^{2}=(m_{p}-m_{d}-m_{e})c^{2}=(m_{p}-(m_{d}+m_{e}))c^{2}=(M_{p}-M_{D})c^{2}$
Hence, proved.