If your daughter is being claimed as a dependent, she cannot claim the baby as a dependent. If her boyfriend lived with you as well in December, he could claim the baby as a dependent. Otherwise, he does not meet the residency requirement and you could claim your daughter and the baby.
See the following requirements from IRS Publication 501:
Relationship - Dependent should be
Your son, daughter, stepchild, foster child, or a descendant (for example, your grandchild) of any of them, or
Your brother, sister, half brother, half sister, stepbrother, stepsister, or a descendant (for example, your niece or nephew) of any of them.
Age - Is the child under 19, or between 19-24 and a full time college student?
Residency - Did the parent lived with the child for more than half the year (or the majority of the year from the date of birth)?
The child cannot be claimed as a dependent if they provided more than half of their support.
For older children, the cannot be claimed as a dependent if they file a joint return.
