Kimcha D’Pischa must be given generously. The poor must be given enough to cover all their needs and for them to have enough to last even after yomtov.
It is related that Rav Yissochor Dov of Belz zy’a asked one of his attendants before Pesach if a certain pauper was already given money for his Pesach needs. The attendant answered in the affirmative. The Rebbe then asked how much the man had been given, and the attendant answered that he was given enough to purchase matzohs, wine and apples.
The Rebbe said, ‘That isn’t enough. If you want him to really be able to enjoy yomtov, you must give him enough money so that he will be able to buy food for his family after Pesach. If you don’t give him that much, he will be worried throughout yomtov about how he will feed his family afterwards.’