Per IRS Publication 17 Your Federal Income Tax (For Individuals), page 25:
If your spouse died in 2019, you can use married filing jointly as your filing status for 2019 if you otherwise qualify to use that status. The year of death is the last year for which you can file jointly with your deceased spouse. See Married Filing Jointly, earlier in the instructions.
You may be eligible to use qualifying widow(er) as your filing status for 2 years following the year your spouse died. For example, if your spouse died in 2018, and you haven't remarried, you may be able to use this filing status for 2019 and 2020.
This filing status entitles you to use joint return tax rates and the highest standard deduction amount (if you don’t itemize deductions). It doesn't entitle you to file a joint return.
Eligibility rules. You are eligible to file your 2019 return as a qualifying widow(er) if you meet all of the following tests.
After the two years, you may be able to file as Head of Household, if you qualify.