In your answer to this consider the ways in which Dickens sets out to centralise the family unit in relation to happiness and contentment - and the lack of it which highlights the errors in Scrooge's life.
In the past, we see a young Scrooge not spending christmas with his family, he loved Fan but he is distant from her, favouring school over his family, this lack of a familial connection sets Scrooge on the road of miserly misery that he finds himself on in later life.
He had a pseudo family in the Fezziwigs, which also fell apart because of his coldness. He had a chance of a family with Belle, which he did not fight for and in the end she found familial happiness with another.
In the present Scrooge see's the joy a family can bring and what he is missing out on. The Cratchetts are poor, they have little in the way of financhial hall marks of happiness and yet they are content and happy because of their connections to each other.
His nephew is Scrooge's 'real' family and yet his coldness means that he is missing that connection, and the warmth that that can bring.
The future shows Scrooge the results of his rejection of family and community. Ultimatly Dicken's 'idea' of family is broader than mere blood. It is about comminity and brotherhood with fellow man. Scrooge must care for the poor and destitute he sees as though they were family -as opposed to his initital belief that the poor should go to work houses or die 'and decrease the surplus population'
Scrooge realises that 'Men’s courses will foreshadow certain ends, to which, if persevered in, they must lead' - Scrooge has rejected family and so in the end he too will be rejected, unless he alters those ways.
We know that Scrooge has been redeemed, when he accepts family, when he goes to his Nephew and we find a telling paragraph summing up the alterations to him:
"Scrooge was better than his word. He did it all, and infinitely more; and to Tiny Tim, who did not die, he was a second father. 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. Some people laughed to see the alteration in him, but he let them laugh, and little heeded them; for he was wise enough to know that nothing ever happened on this globe, for good, at which some people did not have their fill of laughter in the outset; and knowing that such as these would be blind anyway, he thought it quite as well that they should wrinkle up their eyes in grins, as have the malady in less attractive forms. His own heart laughed: and that was quite enough for him.”
He has accepted family and brotherly connection with others, acknowledging the interconnectedness of lives.