State Filing

Each state has its own filing requirements so you would have to check each one separately to see if there is a filing requirement (you can add to this post and someone can check for you).  Even if not required to file, she would be able to get a refund of the withholding if she files (although this sometimes does not make sense depending on the amount).

Q. Does she need to file in each state?

A. Yes, probably.  As the other reply said, the rules vary by state.  Here's a link to each state: 

https://ttlc.intuit.com/community/filing-and-paying-taxes/help/do-i-need-to-file-a-state-return/00/25575

For state filing requirements, the  work state (WS) does not, usually, go by what you earned in their state but by your total income . For example, if WS has a $10,000 filing requirement and your total income for the year was $15,000; you would be required to file even though you may have had only had $300 of income in that state. But if your total income was $9,000 you would not need to file.

This is the general rule: The income is work state (WS) source income since it was earned there. Resident States (RS) tax all their resident's income, regardless of where earned. You will file a non-resident tax return for the WS and report the WS income. You will file a full year resident return for the RS, reporting all your income. The RS will give you a credit, or partial credit for any tax paid to the WS.

TurboTax charges $45 for each additional state return prepared.