"During the war, they stole our money and houses."
Translation:Dum la milito, ili ŝtelis niajn monon kaj domojn.
The fact that niajn is a plural adjective and monon isn't a plural noun throws me off a bit. I understand that money has an implication that it's a quantity, but shouldn't it still be monojn?
The correctors agree with you. I have written "nian monon kaj niajn domojn" and it was accepted.
In English, the adjective and verb should match the quantity. "They stole my money and house" references stealing multiple things (money and house). Likewise, in Esperanto, it would be 'niajn', as the adjective is plural and a direct object. Both things being stolen are direct objects of stealing.
Money is a mass noun, and so is not plural. One dollar is singular; ten and twenty dollars are plural; and one, ten, or twenty dollars are all money (mass). Money and houses makes up two things (never mind that one of these is plural), so is plural.
I got the multiple choice and one of them was. Dum la milito ili stelis niajn monon kaj nejbarojn. I feel like the neighbors should be more important than the money and houses.