Final answer:
Based on provided literary examples, the stepmother's most likely motivation towards her stepdaughter is jealousy. Classical narratives and historical portrayals typically depict stepmothers as envious, leading to harmful actions against stepchildren.
Step-by-step explanation:
The literary references provided suggest that the most likely motivation of the stepmother towards her stepdaughter is jealousy. This is a common theme in classical and historical texts where stepmothers are often portrayed negatively. For example, the classic motif of a stepmother's jealousy leading to evil deeds is evident in the excerpt mentioning 'The vengeance by a jealous step-dame ta'en.' The narrative of Medea sending a poisoned cloak due to jealousy over her ex-husband's new marriage further supports this notion. Roman and Greek portrayals of stepmothers, as mentioned, typically involve harmful actions driven by selfish motives to ensure their own children's inheritance or to gain control over the household, which can be rooted in jealousy of the stepchildren's position or inheritance rights.
Looking at the context and historical portrayals, the stepmother's actions likely stem from jealousy rather than fear, love, or greed. While these other motivations may also play a role to some extent in different narratives, the provided excerpts do not support these as the dominant motivations.