If your daughter is the only possible custodial parent given the father's incarceration there are several things she should do. First she should get an order of custody in place if she has not already. The second she as a parent should have a will a living will and health care proxy. These are things we often avoid because when you are you if you think nothing will happen. Unfortunately life is uncertain. That being said it is great that you are thinking ahead but also is there a reason to think she will face a long hospitalization? One where guardianship wod be needed immediately. She should sit down with an attorney to discuss her options. I hope you found this helpful.
The above answer does not constitute an attorney client relationship and/ or retention of counsel. This answer is based upon the facts presented and may change if additional information is provided. The rules of the Bar for New York State may require me to advise that this could be construed as attorney advertisement.
There are good family law firms in your area. Consult one of them about having your daughter execute the appropriate advance directives given your situation. You can call the Buffalo Bar Association or the Niagara County Bar Association for a list of attorneys they recommend.
your daughter would have to execute certain documents to appoint you the guardian in case of her incapacity. She and you should seek legal help in completing the the appropriate documents.
This advice is not meant to create an attorney-client relationship and is a general anwer to the question posed.