Did you file first and say that no one else could claim you as a dependent? If so, you have blocked your mother's ability to e-file this year. If you filed a return that the IRS accepted, then your mother will have to file by mail.
When your own return has been fully processed, you will have to amend it. When you amend you will go to My Info. Click your name and go through the screens to the question that asks if you can be claimed as someone else's dependent. You need to say YES. Do not amend yet. Wait for the IRS to process your return. Your parent does not need to wait for you to amend. They can mail her return whenever they are ready. Waiting will not help them.
See this TurboTax support FAQ for amending a tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-change-correct-return-a...
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
