well there are a couple of things this could mean, it could be a precognitive dream, meaning you and your mum may have a large fight in the future, so maybe you should listen in on what your fighting about in your dream to prevent this.
Could just a symbol of honesty and maybe you and your mum need to have a heart to heart chat about something your not being completely truthful with her.
Maybe its nothing, and a quick five minute meditation be4 bed with a sprig of lavender near to keep nightmares at bay, if you consider this as a night mare.
Honestly i think if its a recurring dream, it obviously has a message your not getting, make sure you write your dream down and try to remember what you are fighting about in your dream.
goodluck and thank you for reading