I honestly doubt it will change in either direction no matter the price of oil.
Really it all depends of what your def of " charity" is. The $$$ we give to Israel....that won't change no matter if they have to physically take the last quarter from your pocket, Israel will get their $$$. Other $$$ given to foreign countries, that will stay the same or possible go up.
$$$$ given to homeless, soup kitchen, single mothers, needy children charities -----they're on the back burner for the gov't