If someone knocks on the door collecting tzedaka and a child answers when his father is sleeping should he wake him up or not? The Shevet HaKehosi (5:176) says no. Although the Sefer Chasidim says you should wake your father up for a mitzva since it will make him happy nevertheless tzedaka is different.
Firstly unless the son knows for a fact that his father has enough money to support his family he may not even be obligated to give tzedoka according to some acharonim. Even according to those who say he is still obligated they agree that there is no mitzva to give this particular collector. Additionally the son cannot be sure that this collector is worthy. He may be crook which is all too common nowadays according ot the Shevet HaKehosi. Therefore it is better to ask the collector to come back later unless the father specifically asks to be woken up.
Interestingly the Sefer Chasidim says that Dama Ben Nesina did not wake his father up to get the keys to sell the jewel to the Chachomim because the profit was his alone. If his father would have profited from the sale it would have been permissible to wake his father up.*