**Core Concept**
The question requires knowledge of the latest vaccination guidelines, specifically the recommended vaccination schedule for children at the age of 5 years. The core concept here involves understanding the typical vaccination schedule and the recommended age for each vaccine.

**Why the Correct Answer is Right**
The correct answer is based on the latest guidelines from the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO). At the age of 5 years, children typically receive the second dose of the Measles, Mumps, and Rubella (MMR) vaccine, as well as the second dose of the Varicella (chickenpox) vaccine. This is part of the routine vaccination schedule to provide long-term immunity against these diseases.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the first dose of the MMR vaccine is typically administered at 12-15 months of age, not at 5 years.
**Option B:** This option is incorrect because the first dose of the Varicella vaccine is also typically administered at 12-15 months of age, not at 5 years.
**Option C:** This option is incorrect because the second dose of the MMR and Varicella vaccines are indeed recommended at 5 years of age, but it's not the only vaccine administered at this age. Other vaccines like the second dose of the Hepatitis A vaccine might be given at a different age.

**Clinical Pearl / High-Yield Fact**
It's essential to stay up-to-date with the latest vaccination guidelines to ensure that children receive the necessary vaccines at the correct age to prevent vaccine-preventable diseases.

**Correct Answer: C. Second dose of MMR and Varicella vaccines.**