Conrad Hilton's behavior has been erratic for so long ... E.G. Daily's house was on a security lockdown long before he arrived on her doorstep last weekend.
Sources close to E.G. tell TMZ both she and her ex-husband, Rick Salomon, decided to significantly beef up security measures to protect their daughter, Hunter, from Conrad. Hunter lives with her mom.
We're told it was obvious to them the restraining order against Conrad wasn't working, so they took other measures:
-- 24-hour round-the-clock security ... with a few guards now living at the homes on a permanent basis.
-- Adding lighting and updating security camera sensors ... E.G. gets a direct camera feed to her phone.
-- 2 Rottweilers patrol the grounds.
As we reported ... E.G. says she and her family have had numerous run-ins with Conrad after his 2015 arrest for breaking into their home -- and even though she didn't always call cops ... it's obvious she was preparing for the worst.