She visits the Beverly Hills store often and I have seen her once at the store with her husband, baby, and dog. The H accessories might be her own personal ones that she wears in the show. She carries them well.
Serena's mom was also carrying a blk box kelly! I can't believe I'm admitting this but on the show (since I watch it every week, guilty pleasure), serena's mom is often wearing Hermes accessories. So far I've noticed she's carried another color box kelly and tan ostrich birkin 2 times on the show. I know IRL Kelly Rutherford (serena's moms name IRL) has an impressive Hermes collection herself and even named her son Hermes! LOL =P