The two "visitors" refer to the two business men who approach Scrooge asking for a charitable donation to help the poor and needy "at this time". Scrooge asks "are there no work houses?", are there no prisons?" And the treadmill is that still in use?" . All of which he thought that the poor should suffer because they were poor.
Merely explains that without their council Scrooge may expect the same fate as he was suffering - everlasting torment.
Humbug
The ghosts are the ghosts of Christmas Past, Present, and Future
Scrooge had no more family following Fans death
I am Christmas past.
Marley appeared to Scrooge and warned him about changing his behavior. Marley also told Scrooge he would be visited by three ghosts.
When Marley's ghost visited Scrooge he warned him about the ghosts and his behaviour.
This was Marley telling Scrooge that he (Marley) was allowed to come back to Scrooge to tell Scrooge of his inpending eternal life of torment should he not make changes to the way he lives his life now and sees mankind as his business not just the money he can get from them
Three ghosts
He states its "Christmas day"
They show the reader that he was miserly.
That he was collecting for the poor. He hoped that Scrooge would be generous at this special time. Scrooge questions wheather the prosions, workhouse and treadmill were still in ooperation. he is told they were. Scrooge is pleased to hear this as he is contributing to their opeation in his taxes