How does detail "and someone have little Davy Hutchinson a few pebbles" contribute to the text

This means that little Davie is encouraged to stone, murder, his own mother. This contributes to the twisted irony of the situation.

this means that little Davy is going to contribute to the stoning of his mother;

Explanation:

This contributes to the twisted irony of the situation, that the tradition is more important than family ties.

the tradition is continuing / being taught to the younger generation;