Mistress Anni had an issue with her boyfriend and she did not want to let things end without her humiliating him and punishing him for it. That is why she chose to trample him and turn him into a foot slave so that he would learn to fear her and to do things her way. Or at the very least consult her before he did things. She did not want to be ignored.
Mistress Van Licks and lady BlackDiamoond as well as lady Adora wanted to degrade these foot slaves because they had gone against their wishes. The mistresses had told them what they wanted them to do but the guys did not adhere to that. They pissed the mistresses and they had to go out of their way to humiliate them. They were humiliated while naked and got trampled and crushed. In addition, they had to lick muddy feet.