Missing cat

Tabby female cat, about 5 years old. Her name is Eva and she's a very anxious cat. She is scared of loud noice, people, dogs and everything that you can think of. If you try to take her, she will run away and hide in a safe place for her. Our other cat somehow open the lock of the back door probably at about 5 or 5:30 this morning and the kittens came back but she didn't .