Firstly i want to say i am sorry for not getting this in on time.

The conflict within this story has been identified as Human Verses Human  due to the acts of Mary Maloney towards her husband, and from this text strait from the speech i think that this is the plot type

“At that point, Mary Maloney simply walked up behind him and without any pause she swung the big frozen leg of lamb high in the air and brought it down as hard as she could on the back of his head.”

But it was no always like this, They used to be a Lovely couple together loving each other so contently, but one day Marys husband got back from work one day and laid down so pretty hefty news, that was probably him quitting his job but could have also been him being fired from his job. and this news brought out such emotions that she obliterated his skull with a single hit of a frozen leg of land that was being made for diner,

here are a couple of links to the author

Roald Dahl | Biography, Books, Movies, Matilda, The Witches, & Facts | Britannica

Roald Dahl – Wikipedia