MA can tax all the income she earned as an MA resident. CA can tax all the income she earned as a CA resident, including the income for her one month of remote work done in CA for the MA company. MA cannot tax a non-resident on income from work not actually performed in MA. You became CA residents when you moved into your new home in CA.
If you can't get a corrected W-2 from the employer, and you want to correct the W-2, you do so by filing a Substitute W-2 using IRS Form 4852. https://www.irs.gov/pub/irs-pdf/f4852.pdf
To do this, revisit the W-2 in TurboTax, go through the questions. You'll be asked "Do any of these uncommon situations apply to this W-2?" Check the box that says "Substitute form". That should cause TT to generate Form 4852.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
