If you have qualifying children as dependents, you can have the filing status as a Qualifying Widow for two years after the year of passing of your spouse. In the year your spouse passed away you should have filed as Married Filing Jointly.
IRS Publication 501 page 9 - https://www.irs.gov/pub/irs-pdf/p501.pdf#page=9
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.
