If her main, primary residence is in PA, then for tax purposes she is a resident of PA and she must file a PA tax return. ALL her income would be subject to PA taxation.
As a PA resident, it is not necessary for her to file an NJ tax return unless she has NJ-source income. One example: if she were to rent out her NJ vacation home, the income from that would be NJ-source income and she'd have to file a non-resident NJ tax return (in addition to her PA tax return) to report that income.
Her federal return is not affected by her state of residence.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
