Student State Taxes

It depends. It is best to read the rules for each state.

She will need to file Missouri as a resident but may not have a filing requirement for Minnesota even if her permanent address is still Minnesota based on the instructions and her income. 

See 2020 Minnesota Individual Income Tax Instructions, page 5 for Am I required to file a Minnesota Individual Income Tax return?

The 2020 MO-1040 Individual Income Tax Long Form Instructions define residency on page 4 as:

A resident is an individual who either:

1. maintained a domicile in Missouri or

2. did not maintain a domicile in Missouri but did have permanent living quarters and spent more than 183 days of the taxable year in Missouri.

Exception:

An individual domiciled in Missouri who

did not maintain permanent living quarters in Missouri,

did maintain permanent living quarters elsewhere, and

spent 30 days or less of the taxable year in Missouri is not a resident.

Domicile: The place an individual intends to be his or her permanent home;

a place that he or she intends to return to when absent.

A domicile, once established, continues until the individual moves to a new location with the true intention of making his or her permanent home there. An individual can have only one domicile at a time.

To confirm her residency, check the residency flowchart diagram on page 3 of Form MO-NRI - 2020 Missouri Income Percentage.