Yes. As long as your grandmother meets the tests for claiming a your child as a dependent. Key information is that your child will not be a qualifying child because she does not live with your grandmother, however she can be a qualifying relative for tax purposes. As you indicated, you cannot waive the exemption to the noncustodial parent.
Qualifying Relative:
You provided more than half of their support.
They made less than $4,050 in gross taxable income. (Social Security income generally doesn’t count here.)
They live with you (365 days in the year) or they are related to you.
They aren’t a dependent on someone else’s taxes.
They aren’t doing their taxes with a spouse (married filing jointly).
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They are a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
You can’t claim a dependent if you are a dependent on someone else’s taxes. Use the link here for more information. Rules for Claiming a Dependent on Your Tax Return
IRS Worksheet to Determine Support (click this link to print the worksheet)
