There are two types of dependent, qualifying child and qualifying relative.
Your child can't be a qualifying child dependent if she is 19 or older and not a full time student. She can be a qualifying relative dependent if she has less than $4150 of taxable income, you provide more than half her support, and she is not a "taxpayer" this year. She is a taxpayer if she files a return and claims any dependent or credit other than a simple refund of withholding. You will need to make sure that she either does not file, or if she does, she checks the box that says "someone else can claim me as a dependent"; and she does not try to claim your grandchild as her dependent.
Your grandchild can be your dependent if she lived in your home more than half the days since she was born (select "lived with us the whole year" in Turbotax), and you have more taxable income than her mother, and as long as her mother does not try to claim her as a dependent.
If your daughter filed a joint return with her spouse, she can't be your dependent. Your grandchild can still be your dependent but only if your income is higher than the combined income of your daughter and her spouse on their joint return.
