She appears to be the daughter of Kendo, the gun shop owner.
In the following video, skip to 5:44 to see the relevant footage:
Kendo: "Non dirmi come trattare mia figlia" =
"Do not tell me how to treat my daughter"
Ada: "Spostati. Va eliminata prima che si transformi" =
"Move away. It must be eliminated before it transforms"
Kendo: "Eliminata? E la mia bambina, cazzo!" =
"Eliminated? That's my little girl, ***hole!"
EDIT: The damned video was removed from YouTube. It was uploaded by an Italian YouTube channel, and the cutscene had Italian subtitles - that's why I provided English translations. If I find the footage in another video, I'll post it here.
The following images of Kendo and the girl reveal more information about the relationship between the two characters:
https://i.imgur.com/AreBITs.jpg
https://i.imgur.com/c6ls8cI.jpg
https://i.imgur.com/aYlWuz0.png
And, here's a tweet from the official Resident Evil community manager, which confirms that the man is Kendo:
https://twitter.com/ImKatastrophe/status/1069984630982500354