Benthemite philosophies and Malthusian economics are addressed through a conversation Scrooge has with the poor unsuspecting person who accosts him towards the beginning of the novel to ask him for a charitable donation at Christmas time. Scrooge refuses because of the existence of the Union Workhouses and the Prisons, and the Treadmill and the Poor Law. His argument is that because society already makes provision for the poor there is therefore no need for charity. This directly relates to the teaching of Jeremy Bentham and his utilitarian philosophy through the poor being regarded as a minority in society and therefore not being the important focus of everybody else.
Malthusian economics is referred to when Scrooge is told that the poor "would rather die" than live in the houses. Note his response:
"If they would rather die," said Scrooge, "they had better do it, and decrease the surplus population."
Malthus argued that if somebody was not able to earn enough to provide for himself or had nobody to provide for them, they had no right to take up vital food and water as they did nothing to contribute towards society, and therefore they should die. The "surplus population" is a direct reference to his ideas. Both concepts addressed in this question are related with very harsh approaches to poverty and society, and therefore it is entirely fitting that Scrooge should be associated with them at the beginning of this text, to make his U-turn all the more dramatic by the end.