I am filing taxes for a friend. He is a resident of one state and had income in that state. But, he was in prison in another state on the last day of 2014. He will return back to his home state in early March. The tax form asks where he lived on the last day of 2014. What do I enter - his state of residency or the other state where he was in prison.

aslongas he is/was a full year resident of the state before he was in another state, then he needs to file his return with the state where he lived and worked before he went to jail in another state.