Mother in Law

A parent or other closely related person does not have to live in your home to be claimed as a dependent under the Quailfying Relative rules, as long as they meet all the requirements.

Go back through the Dependent section in My Info and make sure that you did not indicate she was your child.  You should have selected Someone Else on the Who do You Support? screen.  Then from the dropdown select Parent

To be a Qualifying Relative -

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 income for the year must be less than $4,200 (social security does not count) 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 or a U.S., Canada, or Mexico resident for some part of the year.
6. The person must not file a joint return with their spouse.