Talk to her case worker.
There may be concerns about placing the child with you that have nothing to do with your state of residence, but it's also possible that the problem is that the court could lose jurisdiction if the child moves to another state.
Also, if the child has a stable foster care placement, the court may view it as better for the child to maintain that situation even if a relative's home is available.
If you are serious and can't get support from the child's case worker, consult a lawyer in the state where the child is located.

