Her intent to only be in NY temporarily is a factor. From what you describe, she should file a NY non resident return and a PA resident return. She will pay tax to both states. But, PA will give her a credit, or partial credit, for the tax paid to NY. Prepare the non resident return first.
In taxes, a temporary absence is described as one expected to last less than one year. As the other reply indicates, other factor could come into play.
