I want to ask the nanny to buy food and cook, but I am worried that she will steal money. What should I do?

Don't be too generous at ordinary times, wear ordinary clothes, don't show off your wealth, don't look rich, buy things and sell vegetables with a nanny's receipt, and don't put valuables at home. If not, you can try for a while. From the other side's point of view, the nanny just comes out to work. No one will invite the matron after stealing her things, which will ruin your own fortune.