Is she living in PA as her permanent residence or is this an internship or something?
Since TX does not have a state tax, she obviously does not need to file a resident return. However, she will need to file an Illinois non resident return for the time she was a student and earned money in IL. If she is not staying in PA, and only there temporarily, then she will need to file a PA non resident return as well claiming the income she received while working in PA.
If her move to PA is permanent, or not just a temporary thing for a temporary job (meaning she plans to be there less than a year and will then return to TX), then she will need to file a PA resident return, claiming the income she earned while living in PA and a IL non-resident return for the income she earned while living there.
Either way, she will need to file 2 state returns, it just depends on her intentions in PA.
Multiple states- Where to file
Part year resident returns.
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