https://www.irs.gov/pub/irs-news/fs-05-07.pdf
I think Head of Household and so do Turbo Tax https://ttlc.intuit.com/community/taxes/discussion/can-t-i-change-filing-status-to-qualifying-widow/....
IF they ever adopted the child, then they could qualify for using "child" and Qual Surv Spouse.
Here's wishing you many Happy Returns
