Final answer:
The text does not specify who killed Nancy for helping Oliver escape. Historical violence related to anti-slavery efforts is discussed, illustrating the danger faced by those helping slaves, but the exact answer to the student's question isn't provided in the text excerpts.
Step-by-step explanation:
The provided excerpts do not contain a direct answer to the query about Nancy. However, they do discuss historical acts of violence related to helping slaves escape or expressions of anti-slavery sentiment. People involved in such acts often faced severe repercussions from pro-slavery individuals or groups, including violence and even murder.
The tragic story of Margaret Garner, for example, underscores the desperation and violence surrounding the issue of slavery, as she killed her youngest daughter rather than see her enslaved. In similar historical contexts, individuals who helped others escape from slavery could indeed be targeted and killed by those who opposed such acts. The precise answer to the question about Nancy, though, may originate from a work of fiction or historical event not directly referenced in the provided text skeletons.