We cannot tell how much money that had? That is not right. There are lots of clues in this painting to tell us how much money this family had.
They're not poor either. A family that had no money couldn't afford such expensive clothes.
The correct answer is that the family was wealthy. Only rich people could afford the luxury of having a portrait painted. There are also clues in the painting itself. Look at the mother's jewels, the expensive costumes and the land we can see in the background.