Statement-I : The point A(3, 1, 6) is the mirror image of the point B (1, 3, 4)  in the plane $\mathrm{x}-\mathrm{y}+\mathrm{z}=5$

Statement-II : The plane $\mathrm{x}-\mathrm{y}+\mathrm{z}=5$ bisects the line segment joining A(3, 1, 6) and B(1, 3,. 4)

The image of the point A(3, 1, 6) with respect to the plane $\mathrm{x}-\mathrm{y}+\mathrm{z}=5$ is $\left(a,b,c\right)$ 

Then 

$$\begin{gathered} \frac{a-3}{1}=\frac{b-1}{-1}=\frac{c-6}{1}=\frac{-2\left(3-1+6-5\right)}{1+1+1} \\ a-3=-2,b-1=2,c-6=-2 \\ a=1,b=3,c=4 \end{gathered}$$

Thereffor,e the image is $\left(1,3,4\right)$

S-1 and S-II are true 

S-II is correct explanation for S-I