The Convergence of the Twain - S5-E2
Continuity mistake: Norma's headstone gives a year of death as 2015. It also gives Norman's birth year as 1995, making him 20 when she died, but it is repeatedly stated that Norman is 18 when he enters Pine view, and Norma died 2 weeks later.
Suggested correction: Norma doesn't die 2 weeks after they move to Pineview, she dies roughly 2 years later. Dylan & Emma have a baby, then in later scenes a 2/3 year old child.
Pineview Institute is the mental hospital Norman enters (during season 4) and they say he's 18 and has to sign the consent forms. Then at the end of season 4, Norman kills his mother (Norma), which is about 2 weeks later. The city the Bates moved to is White Pine Bay. In season 5 (which is set 2 years after season 4 ends) every time we see Norma, it's Norman hallucinating as she's already dead.
She didn't die two weeks after she moved to white pine bay, she died two weeks after she got married to Alex.