In general we do not differentiate between "how much" and "how many"
E.g. "How much milk" = "Скільки молока", "How many years" = "Скільки років"
But since the answer is four it cannot possibly be how much in English, you know :) If the answer is four, the thing asked about must be countable! Therefore it's "many"
Yes, "money" is uncountable, but if we're talking about what sounds natural and how English is actually used, then that doesn't matter. People regularly ask "how much" when they want to know the price of a thing and are answered X dollars, X pounds, or just a number.
My point is the English exchange "how much?" - "four" does happen (all the time), so such wording should be permissible when teaching English speakers its equivalent in Ukrainian.