Complex sentence: Odd goes to visit his mother at the retirement home, which only makes him more unhappy: his mother is senile and spends her days staring emptily out the window, and the visit reminds him of his own impending old age.
Split into simpler sentences: Odd goes to visit his mother at the retirement home, something that makes him only more unhappy. His mother is senile and spends her days staring emptily out the window, and the visit reminds him of his own impending old age.