You need your 2018 AGI to efile 2019. The AGI is on 2018 1040 line 7. If you filed a Joint return you use the same AGI for each spouse How to find the AGI.
https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/01/25947
Sorry to ask but did your spouse die in 2019? There is a problem with Efiling when one spouse died during the year. You have print and mail your return this year.
