What meaning does the suffix -ence give to the word decadence?

Mark Twain was so disgusted with the social and political decadence of the late 1800s that he called that period "the Gilded Age"
Case of decay
Fear of delay
Onset of decay
State of decay

The suffix -ence gives the word decadence the meaning of "state or quality of." Therefore, the word decadence refers to the state or quality of being decadent, which typically implies a state of moral or cultural decay or decline.