"During the war, they stole our money and houses."
Translation:Dum la milito, ili ŝtelis niajn monon kaj domojn.
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.