I want explanation for point B please

I didn't get it. Can you give me some more details?

What we know here is that the median for X= median for Y and from the graph we see for variability for town X than town Y, indicating that s.d of X> s.d of Y. Lets move on to the options now.

A- This is not necessarily true. Range is simply max–min and while the variability differs, they can still have similar max and min values or different ones so this is incorrect.
B- True, since town Y has values more concentrated around the µ than town X.
C- True. This has been already inferred.

OFFICIAL SOLUTION -

2nd and 3rd only. The first statement is not necessarily true. Range is calculated this way: Largest value – Smallest value. From the graphs as shown (assuming that they do not continue “off screen” left and right), it is possible that the two distributions have the same range, because the distributions are above zero on both the far left and the far right. (In the real world, the graphs might even continue off screen, leading to even less confidence about the range of each distribution.)
The second statement is true. The graph on the right (Town Y) has a smaller standard deviation (it is less spread out around its mean). So families in Town Y are more likely to be within 1 family member of the mean than families in Town X are.
The third statement is true. The graph on the left is more spread out, so it has a larger standard deviation.