In Soil Mechanics and Foundation Engineering, managing settlement due to subsoil moisture movement is crucial for maintaining structural integrity. Settlement can cause severe problems for structures over time. One effective technique to mitigate this issue is providing plinth protection and ensuring proper compaction. Let's analyze the options:

1. Increasing the height of the masonry wall structure: This option focuses on structural change without addressing subsoil moisture movement. It doesn't prevent differential settlement induced by changes in moisture content.
2. Providing plinth protection and proper compaction: Plinth protection acts as a barrier reducing water infiltration near the foundation. Proper compaction of soil increases its density, reducing voids, and leading to better resistance against moisture-induced movement. This directly addresses the cause of settlement, making it the correct solution.
3. Adding additional reinforcement within the foundation system: While reinforcement strengthens a structure, it doesn't prevent settlement caused by subsoil moisture. It merely provides additional stability to withstand loads, not moisture changes.
4. Reducing the thickness of the foundation wall structure: Reducing thickness can weaken a structure and does not relate to controlling moisture movement in subsoil, potentially aggravating settlement issues.

Therefore, the most effective way to limit settlement due to subsoil moisture movement is by providing plinth protection and proper compaction, ensuring a stable and moisture-protected foundation.