It is hard to beat Aunt Polly inviting Dr. Chilton back into the house, combined with Pollyanna's reaction when she sees him. Unless it's when Pollyanna says that the loss of her legs just might be worth it since it got her aunt and the doctor back together.
In the movie only: Pollyanna tells crabby old Mrs Snow a story about how she always wanted a doll for Christmas but never got one. At the neighbourhood Bazaar when Pollyanna goes to a stall where everyone gets a surprise toy, Mrs Snow sneaks under the stand and makes sure Pollyanna gets a doll. Possibly the most Heartwarming defrosting of an ice queen ever.
Pollyanna's talk with the Reverend Ford, with him coming to the ralization that he's been both a total dick, and a pawn of Polly Harrington.
Reverend Ford: (reading Pollyanna's locket) When you look for the bad in mankind, expecting to find it, you surely will. - Abraham Lincoln.
Pollyanna: He was President.
Reverend Ford: Yes, I know... but I've never heard *that* before...