Does my 89 year old mother, who's income is SS, deceased husband's pension and a small interest from savings account need to file 2019/2020 taxes? Covid last year, nofile

In the past, AARP came to Senior Living but Covid last year made them cancel appts.  She usually gets a small refund.  I want to do her 2020 taxes, but I think I must do 2019 first?? Suggestions?