The question asks for the winner of the 2024-2025 Ranji Trophy among the given options. The Ranji Trophy is a domestic first-class cricket championship played in India. Here is a step-by-step explanation to determine the correct answer:

1. Understanding the Ranji Trophy: The Ranji Trophy is one of India's premier domestic cricket tournaments, showcasing teams from various regional and state cricket associations.
2. Analysis of the Options:
   • Kerala: A competitive team but not typically the most frequent winner.
   • Vidarbha: Known for a strong cricket performance in recent years, having clinched titles before.
   • Karnataka: A historically successful team with several Ranji Trophy wins.
   • Saurashtra: Another strong team with recent accolades.
3. Correct Answer Justification: According to the provided information, the winner of the 2024-2025 Ranji Trophy is Vidarbha.
4. Conclusion: While all teams are competitive, based on the latest data for the specified period, Vidarbha emerged as the winner. This conclusion is drawn directly from the answer provided.

Thus, Vidarbha is the correct answer for the winner of the 2024-2025 Ranji Trophy.