If you were a full time student from August to December, 2019 and lived with her for more than half the year, she could claim you unless you paid more than half your living cost for the entire year. How much income you had doesn't matter.
Here is a worksheet for determining whether or not you provide more than half your own support. You must include the value of living with your mother for 7 months.
https://www.irs.gov/pub/irs-pdf/p501.pdf The worksheet is on p. 15 of this pub.
Here are the complete requirements from your mother's viewpoint as to whether she could claim you or not:
1. The child must be your son, daughter, stepchild, foster chld, brother, sister, half brother, half sister, stepbrother, stepsister, or a descendant of any of them.
2. The child must be (a) under age 19 at the end of the year, (b) under age 24 at the end of the year and a full-time student, or (c) any age and permanently and totally disabled. The child was a full time student if the child was full time for at least 1 day of 5 different months during the year.
3. The child must have lived with you for more than half of the year. Temporary absences while away at college are considered living with you.
4. The child must not have provided more than half of his or her own support for the year.
5. If the child meets the rules to be a qualifying child of more than one person, you must be the person entitled to claim the child as a qualifying child.
6. The child must be a U.S. citizen or U.S., Canada or Mexico resident for some portion of the year.
7. The child must be younger than you (or your spouse, if filing jointly) unless disabled.
