Janet has failed to perform both due care and due diligence. Because she has not performed as a "reasonable person" person would be expected to perform, she has failed to perform due care. Because she has not adhered to the organizations policies and procedures and taken preemptive measures (the background check) to avoid harm to the company she has failed to perform due diligence.

"Due care pertains to acting responsibly and doing the right thing. It is a legal term that defines the standards of performance that can be expected, either by contract or by implication, in the execution of a particular task." - CISSP Exam Guide, Sixth Edition, Shon Harris, Chapter 9, Page 1023

“Due care is an important topic for the information security profession to understand. It is primarily a legal term used to describe the care a “reasonable person” would exercise under given circumstances. In other words, it is used to also describe what an individual’s or organization’s legal duty is concerned to be. The lack of due care is often considered negligence and in most countries it is actionable by law.” - Official ISC2 Guide to the CISSP CBK, Fourth Edition, Chapter 1, Page 33

“Due diligence is similar to due care with the exception that it is a preemptive measure made to avoid harm to other person or their property. If performed correctly, due diligence leads to due care when needed and avoids other situations where due care may need to be exercised. Due diligence is a practice that should be adopted by the information security professionals as a core tenant of their career.” - Official ISC2 Guide to the CISSP CBK, Fourth Edition, Chapter 1, Page 33