Jayapataka Swami: Interesting question. Nobody ever asked such a question before! I don’t know if you can have them take acaman beforehand and offer the lamp. I don’t know if there are any hard and fast rules for offering lamps. But chanting the holy name, there is no hard and fast rule. So I didn’t hear that there is some restriction on anyone offering a lamp. So the least you can do is offer them acaman, give them a spoon of water in their hand and then they can offer the lamps so that washing of the hand, that is some aspect of cleanliness. Hare Krsna!