A W-2 would not be necessary because nothing is subject to Social Security and Medicare taxes, and no income taxes are withheld.
However, do it anyways. It will solidify that she is your employee. You may even consider filing Forms 941/944 and 940 each year to report the $0 due. Make sure you do all of the requirements for Employees, such as having her fill out a W-4 and I-9, and posting any required Workplace posters.
