After a few months of being reanimated into a zombie, Trisha’s body become unstable (due to her being brought back to life a little too late..) and kept falling apart. Soon, her decay started to effect her eyesight/hearing and then her consciousness (this either happened once or twice… she would randomly not respond to anything and she was back to being… dead, technically). Dr. Novikoff didn’t want to give up and wanted to reunite her with her family, but he reluctantly decided to ask Trisha how she felt about keeping her “alive” after Cyrus tells him to take Trisha’s feelings into consideration (she’s a zombie and can’t feel physical pain, but emotional pain…).
Trisha tells Dr. Novikoff that she would like to see her family again but she didn’t like how she was affecting him (he didn’t sleep much and was constantly worried about her), she accepted that it would be impossible for him to keep her together and alive (..un dead…) and told him to rid her of her consciousness. And so he did.

“It’s okay you weren’t able to help me… You and Cyrus were like my family…”