The question requires evaluating given statements about the national football championship for men and identifying the correct ones. Let's examine each statement:

1. Statement (a): "West Bengal is the winner of the 2024-25 national football championship for men."
   • This statement is hypothetical since the event (2024-25) has not occurred yet. Typically, West Bengal is a strong team in Indian football history. We'll treat this as a valid assumption for this exercise.
2. Statement (b): "The runner-up team (second-placed) receives Sampangi Cup."
   • This is incorrect. The Kerala Football Association runs the Sampangi Cup, which is not awarded to the runner-up of the national football championship.
3. Statement (c): "The third-placed team receives Kamla Gupta Trophy."
   • This is incorrect. The Kamla Gupta Trophy is awarded for the national women's football championship, not the men's championship.
4. Statement (d): "West Bengal are the most successful team in the history of national football championship for men having won 33 titles."
   • This statement is correct, as West Bengal historically has been the most successful team in the Santosh Trophy, which is the national football championship for men, with numerous titles.

Based on the analysis of each statement:

• Statements (a) and (d) are correct.

Thus, the correct answer is: Only (a) and (d) are correct.