As I understand the situation you describe: Duquesne Light is subsidizing certain light bulbs that can be purchased at Home Depot. I take this to mean that a customer can buy the brand of subsidized light bulbs at a lower price than before. Your friend says this is a good idea since it will lead to less power consumption. But if she thinks that the poor will not change their habits in buying things just because their prices change, then the Duquesne Light subsidy will not lead to less power consumption and therefore, it will not be a good idea by her own standard.
Setting aside the condescending tone of her remarks about the poor, what body of evidence can she cite that the poor are more subject to ruinous buying habits than the non-poor? If she lacks evidence, then what argument can she bring forth to show that unlike non-poor human beings, poor human beings do not economize their actions according to their own judgments of value, i.e, they do not value alternatives and choose from among them the alternatives they value more?