In a overly simplistic summary, the required ERISA fidelity bond is coverage for any plan official who receives, handles, disburses, or otherwise exercises custody or control over plan funds. This can include employees who handle payroll-based deferrals, pay expenses out of the plan, or process other similar transactions. The purpose of the ERISA fidelity bond is to protect the plan against fraud or dishonesty.
Fiduciary Liability coverage is not required. It provides coverage for individuals who are fiduciaries of the plan, and as fiduciaries are personally liable for their actions or inaction.
Cyber Security coverage is not required. It provides coverage to the plan or to the plan sponsor for losses attributable breaches in cyber security. This coverage often requires that the covered entity has implemented and actively manages cyber security controls.
The ERISA fidelity bond is cheap relatively speaking and often is used as a foot in the door to offer the other coverages. The cost for each of the other two coverages is increasing as losses continue to mount, and it pays to shop this coverage together with similar coverage for executives and for company cyber security coverage.
CB Zeller is on target - ask questions before you buy. If this is all new to you, shop around, and talk to at least three providers. Buy with eyes wide open.