If you did not check the box on your tax return that you can be claimed by someone else, then you would be eligible for the stimulus check. If you did not check the box and your mother did claim you and you both efiled returns, one of your returns should have been rejected.
If you did check the box, then you will not get it.
If you meet the requirements to be claimed as a dependent by someone else, you are required to check the box that you can be claimed by someone else whether they actually claim you or not. Here are the requirements for someone age 25 by year end 2019 to be claimed as a qualifying relative dependent as your mother would view them:
1. The person cannot be your qualifying child or the qualifying child of any other taxpayer. A child is not the qualifying child of any other taxpayer if the child's parent (or any other person for whom the child is defined as a qualifying child) is not required to file an income tax return or files an income tax return only to get a refund on income tax withheld.
2. The person either (a) must be related to you or (b) must live with you all year as a member of your household.
3. The person's gross taxable income for the year must be less than $4,200 in 2019.
4. You must provide more than half of the person's total support for the year.
5. The person must be a U.S. citizen, U.S. resident alien, U.S. national, or a resident of Canada or Mexico.
