Once Trump lifted the stay on executions there was no way this woman was going to escape the death penalty!
The US just doesn't have the infrasructure, or the political will, to do anything other than punish when mentally ill people, poor people etc etc commit crimes. That this woman committed such a vile crime made it inevitable that she would be executed.
It will take a while before any changes are made. I hope that Biden is the beginning of a more tolerant US*... but it didn't respond to Obama very well, so maybe a bit longer than you'd like to hope!
*As a country, a political entity, not the individual people, cos I know there is a difference!