Emma is really mothering her father here

There's something childlike about Mr Woodhouse. There is a developmental stage where children learn that people think and feel differently. Emma knows that people think differently - she just thinks they're wrong

Funny that Cotter alluded to the narrator being a child, but when he wants to think of happy things, he thinks of Christmas (which I associate with kids getting presents, Santa Claus, etc, so I think of it as a child's holiday)