Because she is not anyone's employee. Schedule C is Profit or Loss from Business. If your box 7 amount is $400 or more, you must file that form.
This is a business. It may not seem like one becase you did not take any official steps to open a business, but it is. Your income and expenses are reported on Schedule C. There are only two ways to report income from labor, as an employee and as an Independent Contractor. If you do not get a W-2 for your work, you must report your income on Schedule C.
