It depends on whether this was her total income for the year. The IRS website says that you must file if your Adjusted Gross Income is >$5 for 2018 (
https://www.irs.gov/help/ita/do-i-need-to-file-a-tax-return). If she is showing a net loss, if this was her only income source, and if she is married filing separately, and if she provided at least 50% of her own support, then she would not have to file.
