The question of "hard money" depends on the economic condition of the couple and the economic condition of the parents. In fact, since your parents agreed to help you take care of your children, they will willingly and diligently take care of your children regardless of whether or not you give them "hard money". After all, the children are their grandchildren and are related by blood.
If you and your husband have high incomes, I think you can give your parents a little bit of money for their hard work. This is a kind of recognition for them to bring up the child, but also shows a filial piety of you. This will make them feel that you don't take them for granted for bringing up your children. As for whether the parents accept it or not, that's their business. Many parents will not take your money if they have a pension or a certain income.
If you and your husband don't have a very high income, and there's very little left over for you to do more than support your family. This kind of life allows you to take out part of the money to give parents "hard work", but also really belongs to the swollen face. In this case, I don't think there is any need to give your parents "hard-earned money". Your parents know your financial situation and won't give you a hard time. Instead, you should help your parents do more work in your free time after work, and buy some clothes for them once in a while, and they will be very happy.
If your parents don't have a pension and need to bring up your children, they are even less able to make money. In this case, you need to give your parents a little money for their hard work. After all, in this society, it is difficult to move forward without money. Let your parents reach out and ask you for money when they need it, and they will feel very bad in their hearts. When you encounter this situation, you have the money to give more, no money to give less.