**Core Concept**
Meningitis is an infection of the protective membranes covering the brain and spinal cord, known as the meninges. It can be caused by various pathogens, including bacteria, viruses, and fungi. The severity and mortality of meningitis depend on the causative agent, age of the patient, and promptness of treatment.

**Why the Correct Answer is Right**
Option b) E.coli, Group B Streptococci is MC cause in neonatal period is correct. Group B Streptococcus (GBS) is indeed the most common cause of meningitis in neonates, accounting for approximately 80-90% of cases. This is due to the bacterium's ability to colonize the mother's genital tract and transmit to the infant during delivery. E.coli is another significant cause of neonatal meningitis, particularly in the first month of life.

**Why Each Wrong Option is Incorrect**
**Option A:** Epidemic is caused by H. influenzae is incorrect. While Haemophilus influenzae type b (Hib) was a leading cause of meningitis in children before the introduction of Hib vaccine, it is no longer a common cause of epidemics.

**Option C:** Hib vaccine is effective in prevention of meningitis is incorrect. While Hib vaccine is highly effective in preventing invasive Hib disease, including meningitis, it does not cover all causes of meningitis. Other pathogens, such as Neisseria meningitidis and Streptococcus pneumoniae, can still cause meningitis even in vaccinated individuals.

**Option D:** Epidemics caused by meningococcus group B is incorrect. Meningococcus group B (MenB) can cause outbreaks and epidemics, but it is not the most common cause of meningitis in the neonatal period.

**Clinical Pearl / High-Yield Fact**
The conjugate Hib vaccine has been instrumental in reducing the incidence of Hib meningitis in children, highlighting the importance of vaccination in preventing bacterial meningitis.

**Correct Answer:** B. E.coli, Group B Streptococci is MC cause in neonatal period