Black Widow's losses would be the other Avengers. Also, potentially, Hawkeye's family (who consider her 'Auntie Nat').
Banner's would be the avengers and maybe Valkyrie (though I doubt she'll even be mentioned in regards to the snap, really). It could also be Betty Ross, but that would be kind of lame since he hasn't mentioned her name in years. Although, arguably, all of Asgard was Hulk's new family at the end of Ragnarok, so he lost a lot of people, then. Only, Banner never knew most of them - only the Hulk did.
Happy was nowhere to be seen in the movie - no idea if feige or someone else have mentioned his fate at all.