Her father and mother

Are good parents and they have raised Catherine well.

It is noteworthy, by the way, that Mrs. Morland is a very rare character in the Austen menagerie. She is an admirable and competent female authority figure, a type otherwise very thin on the ground in Austen. Mrs. Dashwood, Mrs. Bennett and Mrs. Price all have clear and obvious deficiencies as mothers. Mrs Allen, Mrs. Jennings and Lady Catherine de Bourgh are all figures of fun in the end. Mrs. Woodhouse is dead. Anne Taylor is too much of a friend to be a good governess.

Why does Austen have so few admirable female authority figures? I don't think it is because she didn't think they existed. I suspect it's more of a literary requirement: if the young women in these stories had competent female authority figures overseeing them, they wouldn't get into trouble. At the same time, parents are always a limit on the horizon of the heroine or hero of a story. Any respectable children's story gets them off stage right away.

And Austen does just that in Northanger Abbey. Having established that Catherine's parents are good parents, she quickly gets Catherine away from them and into the hands of the ridiculous Mrs. Allen. Otherwise, the story simply could not happen.