Capability maturity models (CMMs) are frameworks that help organizations assess and improve their processes in various domains, such as software development, project management, service delivery, and cybersecurity1. CMMs define different levels of process maturity, from initial to optimized, and describe the characteristics and best practices of each level. By using CMMs, organizations can benchmark their current processes against a common standard, identify gaps and weaknesses, and implement improvement actions to achieve higher levels of process maturity2. CMMs can also help organizations align their processes with their strategic goals, measure their performance, and increase their efficiency, quality, and customer satisfaction3.

Therefore, the use of CMMs would best enhance a process improvement program, as they provide a systematic and structured approach to evaluate and improve processes based on proven principles and practices. Option C is the correct answer.

Option A is not correct because model-based design notations are graphical or textual languages that help designers specify, visualize, and document the structure and behavior of systems4. While they can be useful for designing and communicating complex systems, they do not directly address the process improvement aspect of a program.

Option B is not correct because balanced scorecard is a strategic management tool that helps organizations translate their vision and mission into measurable objectives and indicators. While it can be useful for monitoring and evaluating the performance of a program, it does not provide specific guidance on how to improve processes.

Option D is not correct because project management methodologies are sets of principles and practices that help organizations plan, execute, and control projects. While they can be useful for managing the scope, schedule, cost, quality, and risk of a program, they do not focus on the process improvement aspect of a program.