Right in the very beginning, when Fly adopts Babe. Babe more then returns the favor after her pups are weaned and sold, coming over to a very depressed Fly:
"May I call you 'mom'?"
When Hoggett is caring for Babe after the latter got sick while singing and dancing "If I Had Words", and the end of the movie.
"That'll do, pig. That'll do."
Also, Rex finally accepting Babe's role in the farm and encouraging him to get better after he started drowning in despair.
"Come on, son. Pull yourself together. The boss ... needs you."
Mr and Mrs Hoggett are polar opposites, but they are very sweet together, especially the scene where Mrs. Hoggett departs on a Bingo Tournament, and Mr. Hoggett holding an umbrella for her all the way to the coach.