Might want some clarification of what is expected of you -
What is their definition of "light housework"?
Hours?
Grocery shopping - pick them up and take them? or go to the store by yourself?
And what you expect from them -
Compensation?
Will you be treated as an employee and the money earned as taxable income?
Mileage?
I'm sure that this will evolve as you get to know their needs better.