That depends on whether she is changing her domicile. Briefly, domicile is a person's permanent home and you can only have one domicile at a time. See here for PA and NY rules on residency.
https://www.pa.gov/agencies/revenue/resources/tax-types-and-information/personal-income-tax/determin...
https://www.tax.ny.gov/pit/file/nonresident-faqs.htm
If your daughter is changing her domicile (residency), then she owe a resident tax return to PA for income paid while she is a PA resident, and she owes tax to NY for income paid while she lives in NY. Assuming she doesn't move exactly on December 31, she would file as a part-year resident of each state.
However, you describe that she is not changing her permanent residence (domicile). That means she must file a PA tax return to report all her world-wide income, even if it was paid while she was living elsewhere. Then she is either a NY non-resident or an NY statutory resident. She is a non-resident if NY is not her permanent home and she lived in NY less than 183 days of the year. She would file a non-resident NY return that only reports NY income, and a PA resident return that reports all her worldwide income, including her NY income. PA will give her a credit against taxes paid to NY on the same income.
But, if she is a statutory resident of NY, she would file as an NY resident and report all her worldwide income for the year, as well as filing a PA resident return reporting all her worldwide income. PA may give her a credit but this is more complicated when a person has two states of residence. NY considers you a statutory resident (resident by law, if not in fact) if you live in NY at least 184 days AND maintain a permanent abode for "substantially all of the taxable year". An abode is a permanent dwelling that has a kitchen and bathroom and is suitable for year round living, even if you don't live there year round. So an apartment is an abode even though it is rented, but a lake cabin or hotel room is not a place of abode.
So you need to look at when she moves. As long as she is not in NY for "substantially all of the taxable year", then you would not need to worry about her being a NY resident, she would be a non-resident. She should have NY tax withheld, and she may need to make estimated tax payments to PA, depending on what her other income is that is not NY income (like investments, gambling, bank interest and so on.)
