Mary would probably have twitter/instagram accounts to promote her performances and when she'll be competing in contests. When not promoting she'd probably be tweeting about cute/funny things in day to day life, cute pics of her team and/or Jin, talking about her favorite scary movies, etc.
Later on, her daughter Jade would also have a lot of social media presence. She'd be closer to one of those "influencer" types. Posting vlogs talking about exercise advice, fashion/makeup tips, laughing at bad fight choreography in tv and movies and breaking down how you'd actually want to fight in those scenarios. She's pretty well rounded, haha. Her family and friends also make frequent appearances on her posts.