While Helen continued to talk with Mary and Samuel and got up to date with what they were doing while she was in Harlow city, Elaine wasted no time hiring her own private investigator to get started on looking into Helen and what she could possibly be hiding. Why wait when she could quickly learn what secrets Helen was hiding.
This wasn't even about Helen dating Eli anymore. No! Elaine wanted to destroy the cockiness she saw in Helen yesterday when she visited the business Helen owned. Being a vampire, Elaine had pride just like any other and the way Helen spoke to her did not sit well with Elaine. Helen needed to be put in her place, kind of like Sarah.
If things were in Elaine's favor, she would've just killed Helen by now but she had an idea of how her son would react. Eli might actually kill his own mother rather than just choke her like at the masquerade party.