The force that acts on the body is only gravity force, so by the time it hits the ground the force will continue being the gravity force that is F=M.g

You can also see this by calculating the time a body takes to fall from a height h : h=v0.t+0.5.g.t^2 so you have v0=0 and t= √(2h/g)

Now replace it on your ecuation a have that F=M.g

The only force that acts on the body is gravitational force. By the time it hits the ground, the force will keep operating $F=Mg$

You can also see this by calculating the time a body takes to fall from a height $h$: $$h=v_ot + \frac{1}{2}gt^2$$ so you have $v_0=0$ and $t= \sqrt{\frac{2h}{g}}$

Now replace it in your equation a have that $F=Mg$