OK, let's try this again.
The general rule is that if your child is under age 24 while being a full-time student, you can claim her as a dependent if she lives in your home more than half the year, and does not provide more than half her own support. Even if a child is away at college, they are usually considered to still live at home, on the presumption that their parents’ home is still their permanent home, and college is a temporary absence.
So the first questions are, is your child age 23 or less, and are they a full time student (are they taking enough credits to be considered full time by the nursing school)? If the answers are yes and yes, then you can claim your child as a dependent. You can also claim your grandchild as a dependent, presuming the grandchild also lives with you.
However, there are two exceptions.
First, if your child files a tax return and claims your grandchild as her dependent, then you can't claim either of them. If your daughter works, then she might qualify for the child tax credit and EIC if she claims the child as a dependent. But if she doesn't work, she won't get anything for claiming her own child as a dependent, and it would probably be better for you to claim both the child and grandchild.
Second, if your daughter gives the father of her child a written release form, then the father can claim the child as a dependent, even if he does not live with the child or the mother. In that case, you can claim your daughter but not your grandchild.
If your daughter is age 24 or older, or is not a full time student, then you may still be able to claim your daughter as long as you pay more than half your daughter's expenses, and your daughter has less than $4700 of taxable income.
Even if your daughter is age 24 or older, or is not a full time student, and has more than $4700 of taxable income, you can still probably claim your grandchild as a dependent, although you would want to compare that scenario with having your daughter claim the grandchild, to see which scenario results in the largest refund or lowest tax.
