Wang Yongshan came not for any other reason, but because the New Year was approaching, and his mother was concerned about her sister and had sent him to deliver New Year's gifts.
In fact, Wang Yongshan didn't usually send gifts in previous years. Firstly, Yang Dachuan was the son-in-law, so if any gifts were to be sent, they should be from him to Wang Yongshan's family. Secondly, with that nasty woman around, the gifts wouldn't reach her sister anyway.
But this year was different. Ever since he went back to his sister's house last time and found out that they had separated households and their lives had improved, his mother kept talking about it to whoever would listen: how her daughter was living so much better now. So, when his eldest brother brought some stuff back from the prefecture, his mother immediately sent him to deliver some on an ox-cart.