In the book of Esperanza Rising Why is Esperanza forced to move to the US?

She is forced to move to the US because after her father dies,

his brother asked esperanzas mother to marry him and she refused because he is a mean man and will make the life bad, that's what esperanza and her mother thought. so tio Luis get mad a burnes her house on fire and they now need to move to the us to work so they have a house