Scrooge is positively giddy to be alive after his exciting, frightening, and transformative evening with the ghosts. He says:

I am as light as a feather, I am as happy as an angel, I am as merry as a schoolboy. I am as giddy as a drunken man. A merry Christmas to everybody! A happy New Year to all the world. Hallo here! Whoop! Hallo!

He shows financial generosity by helping out the Cratchit family. He anonymously sends the Cratchits the prize turkey for Christmas. He also surprises Bob Cratchit with a raise, and he ensures that Tiny Tim gets the medical care he needs so that he doesn't die. He also gives a large donation to the charity helping the poor, when the day before he had said it would be better if the poor died off.

He shows generosity of heart by smiling and saying Merry Christmas to the people he passes in the street. He shows generosity of spirt by visiting his nephew's house for Christmas and being glad to see all the guests, when the day before he had turned down the invitation.

This change is not temporary. We are told Scrooge continues to be generous with his money and his time for the rest of his life:

He became as good a friend, as good a master, and as good a man, as the good old city knew, or any other good old city, town, or borough, in the good old world.

Scrooge donates to the Cratchit family and a charity for the poor.

In the beginning, Scrooge is a miserable miser who does not care about anyone. He complains about giving his clerk Bob Cratchit Christmas day off, and he refuses to donate to the charity collecting for the poor.  All he cares about is himself, and he enjoys being alone and grumpy.

After the visit from the ghosts, Scrooge changes.  The first thing he does when he wakes up Christmas morning is send a huge turkey to Bob Cratchit—without telling him who it is from.  He saw with the Ghost of Christmas Present that the Cratchits would not have enough to eat for Christmas dinner.  The first thing he did was make sure that they had an excellent Christmas.

Scrooge also made a generous donation to the poor.  When he sees the man who came to him on Christmas Eve asking for money, he stops him and promises him what is obviously a very large number.

“Lord bless me!” cried the gentleman, as if his breath were Gone. “My dear Mr. Scrooge, are you serious?”

“If you please,” said Scrooge. “Not a farthing less. A great many back-payments are included in it, I assure you. Will you do me that favour?” (Ch. 5)

We do not hear the number, because Scrooge whispers it in his ear.  However, we can be sure it is a big donation.  Scrooge wants to help children like Ignorance and Want.

Scrooge also makes an attempt to be involved in Bob Cratchit’s life. When he watched the Cratchit Christmas, he got acquainted with and attached to the family, especially Tiny Tim. Scrooge makes it a point to let Cratchit know that he will not only give him a raise but help him financially.

I’ll raise your salary, and endeavour to assist your struggling family, and we will discuss your affairs this very afternoon, over a Christmas bowl of smoking bishop, Bob! Make up the fires, and buy another coal-scuttle before you dot another i, Bob Cratchit!” (Ch. 5)

These two acts both demonstrate that Scrooge is a changed man.  He becomes a second father to Tiny Tim, and looks out for other poor people in his community.  His intervention worked marvelously.  Scrooge realized what a miserable old man he had become, and decided that it was better to have people in his life that he cared about who actually cared about him.