That's a challenging essay question. There are arguments to be made from both sides, and the core of the argument is as old as the ideas of English philosophers Thomas Hobbes and John Locke.
Thomas Hobbes believed that the social contract essentially meant that people will exchange some of their individual freedoms for common security. His treatise, Leviathan (1651) supported a strong central government for the sake of a country's security and stability. So if Hobbes were answering your question,m he'd say that the Department of Homeland Security is proper and needed in order to keep citizens safe.
John Locke's arguments in his Second Treatise on Civil Government (1689) were more focused on the rights of all persons and the protection of those rights in a society. His view of the social contract saw the emphasis as benefiting all persons in their rights to life, liberty and property. So Locke might look with a skeptical eye at the Department of Homeland Security, if it was shown to be infringing on individuals' rights and liberties.