The point of that scene towards the end of the story is to prove to Mr. Scrooge that after his death, not only is he being disrespected, but his possessions have been stolen and are being sold, taken right out from under his dead body. With no family to protect him or his possessions, he is left vulnerable to thieves and opportunists.
It is a way for the Spirit of Christmas Yet To Come to prove to him that his life has no value in relationship to other people. No one will miss him, no one values him enough to respect him even in death. The behavior of Mrs. Dilber is so shocking to Scrooge, so vile, that he is jolted into an eye opening understanding of how little people thought of him as a person. Of particular significance in this conversation is the talk about Scrooge's bed curtains,
"Joe went down on his knees for the greater convenience of opening it, and having unfastened a great many knots, dragged out a large and heavy roll of some dark stuff. 'What do you call this?' said Joe. 'Bed-curtains?' 'Ah.' returned the woman, laughing and leaning forward on her crossed arms. 'Bed-curtains!' 'You don't mean to say you took them down, rings and all, with him lying there?' said Joe. 'Yes I do,' replied the woman. 'Why not?' 'You were born to make your fortune,' said Joe, 'and you'll certainly do it.'" (Dickens)
Mrs. Dilber thought so little of Scrooge that she stripped the bed curtains while he was still lying in the bed. Even though he was laying there dead, she didn't think that it was wrong to take his bed curtains and his blankets and his nightshirt.
"'Don't you be afraid of that,' returned the woman. 'I an't so fond of his company that I'd loiter about him for such things, if he did. Ah! you may look through that shirt till your eyes ache; but you won't find a hole in it, nor a threadbare place. It's the best he had, and a fine one too. They'd have wasted it, if it hadn't been for me.'"
Joe is even shocked when he sees that she stripped his blankets and nightshirt.
It is designed to shock Scrooge into understanding how far removed he is from people. His housekeeper does not even consider him enough to respect his corpse.
When the last of the spirits, the Ghost of the Future, appears to Scrooge in "A Christmas Carol," he takes the old miser to "a low-browed, beetling shop" in a terrible quarter of London that "reeked with crime, with filth, and misery." There sits an old "rascal" of nearly seventy, smoking a pipe near a stove behind a tattered curtain. Into this place come a charwoman, a laundress, and a man in faded black. When they encounter one another, they burst into laughter.
These people are the jackals of society, for they have plundered what things they could obtain from the house of the dead Scrooge. The charwoman has even taken the curtains--to the amazement of even the vile Joe--from his bedroom and stolen the very shirt from Scrooge's back, showing absolutely no respect for the dead. In fact, Mrs. Dilber laughs at the thought of their stealing in this manner from Scrooge. The charwoman scoffs,
'If he wanted to keep 'em after he was dead, a wicked old screw,...why wasn't he natural in his lifetime? If he had been, he'd have had somebody to look after him when he was struck with Death, instead of lying gasping out his last there, alone by himself.'
To this remark, Mrs. Diber agrees,
'It's the truest word that ever was spoke...It's a judgment on him.
Old Joe chalks the sums of what he owes them onto his wall. These acts of the unconscionable people is somewhat suggestive of those who barter over the robe of Jesus, solitary and betrayed by Peter, as He was led to his crucifixion. So, perhaps, Scrooge realizes how greatly he is despised when even the lowest of London society laugh at him and desecrate his corpse, carrying his final belongings to a filthy, disreputable rag shop.
the point is basically to show him that everything he has LIVED FOR will be taken and he will have nobody to protect it because of the way he has lived.