Google Photos will give you a visual list of faces it recognizes in your photos and let you select which one is your mom. Then, you can pick the children — whether that’s you, your siblings, your kids, or maybe close friends that feel like family to you all. After a few minutes, the movie should show up in your Assistant tab.
PS: Looks like it may not work in all regions… maybe Google considers Mother’s Day as region specific?
See https://www.theverge.com/2017/5/4/15545628/google-photos-mothers-day-movie-maker 
Google Photos can turn your pictures into a Mother’s Day movie
Hint: it requires you to have pictures of your mom