Tax question - Should file jointly or separately?

Tax question - Should file jointly or separately?

A couple, hu*****and contributed 2/3 of the whole family income and wife contributed 1/3 income during last year. Hu*****and works in a state that only has federal tax, but wife worked in a state that has both federal and state tax - wife had worked in that state for about 210 days and quitted the job before the end of last year.

At the time filing tax return for last year, should they file jointly or separately to take the most advantage? If file jointly, will the hu*****and's income subject to state tax as well - although he had not lived in that state and earned any income in that state?

BTW: they have no house, no other income and no item deductions,

Please advice.

Thanks,
KY