All ladies are mother and loves their children.
See carefully there is word "their".
∀x(M(x)→L(x)) logic given says, all those things in universe which are x are mother and love x i.e. themselves.
Firstly we need atleast two variables x and y for mother and children, and then we will establish relationships between them, which are following
1. Whatever x we select from universal set, should be a mother ¥x[M(x)].
2. Then that mother should have "her own" as in question it is written "mother love their children not all childern of the world which might include children of other mother too, a mother need to love only her childrens" so Ch(x,y) i.e. x is mother of y.
3. Mother love her children(s) Lo(x,y).
So, all x which are mother and for all children y whoes mother is x, x mother love child y.
¥x¥y runs like a two for loops, first a mother will be selected then inner loop will run for children, who so ever y satisfy Ch(x,y) i.e. choosen x in outer loop is mother of select child in inner loop, it will checked that she loves her that child by Lo(x,y), the y++ check for next y, if he/she is mother x child and check for love condition, and loop goes on and on.
I think you'll get now why above giben is correct.