Character Analysis
Sweet Angels
If John Canty is pretty much pure evil, then Tom's mom and sisters are the complete opposite. They're like Hufflepuffs or Care Bears: they only want to love and take care of you.
The very first description we get of them is actually not the most complimentary: "Bet and Nan were fifteen years old—twins. They were good-hearted girls, unclean, clothed in rags, and profoundly ignorant. Their mother was like them" (2.3).
Now, you might have noticed that The Prince and the Pauper starts out with pretty stereotypical characters and then complicates them: there's the evil king, the pompous prince, and the poor street urchin. With Tom Canty's family, we get two types of stereotypical poor people: evil thieves and goodhearted idiots. You can guess which group Tom's mom and sisters fall into.
Just as John Canty gives us a consistent person to hate, Tom's mom and sisters give us people to root for no matter the situation. We might not always root for Edward, or even for Tom, but how could you say no to nice people like Tom's mom and sisters? We don't want people like this to be poor and abused and unhappy. The fact that people as nice as this have such hard lives makes us realize how urgently change is needed in this society.
Mom Knows
That brings us to the event that changes the whole story. Tom's mom is one of three people who actually believe the prince's claims. It's not because she actually believes what he's saying; it's because of her "motherly instinct." Lucky for Tom, Edward's mom wasn't around to spoil his ruse.
Well, when Tom is on his way to the coronation, his mother spots him and recognizes him immediately:
She embraced his leg, she covered it with kisses, she cried, "O, my child, my darling!" lifting toward him a face that was transfigured with joy and love. The same instant an officer of the king's Guard snatched her away with a curse, and sent her reeling back whence she came with a vigorous impulse from his strong arm. The words "I do not know you, woman!" were falling from Tom Canty's lips when this piteous thing occurred […] (31.13)
Now, if Tom's mom weren't basically a personification of goodness, we would never believe that she could have such an impact on him. After all, she makes him want to give up being the king of England. That's some serious love right there, and we're not really surprised: Twain has made Tom's mom the sort of person worth giving up jewels and riches for.
Lucky for Tom, by choosing his family over money and status, he proves his own goodness. The result? In the end, he gets money, a long life, and fun times with his family. Not a bad deal.