The National Rail Museum in Delhi is an ode to the rich history of the railway system in India. However, when it comes to food, the museum itself does not have a storied culinary history since it's primarily a showcase of India's rail heritage. Nonetheless, visitors can find basic snack kiosks and a cafe within the museum premises which cater to the hunger pangs one might experience during their exploration. Traditional Indian snacks and beverages are commonly available here.
Please note that since you have mentioned not including cow-related non-veg food, all the famous dishes listed here are vegetarian. Moreover, while the mentioned restaurants may not be located inside the National Rail Museum, they are revered dining establishments within a reasonable distance from the museum and offer an authentic taste of Delhi's diverse cuisine.