There are many restaurants along the yatra route that remain open 24*7. You will get food without onion and garlic. There are shrine board bhojanalayas as well (including one at Ardhkuwari). You will get coffee, tea, Maggi and simple Indian food like Rajma Chawla. There is a Sagar Ratna restaurant at Ardhkuwari.
Here are the top 4 restaurants in Vaishno Devi:
1. Prem Lahori Vaishno Dhaba
Ban ganga road., katra, Katra, India
Indian
7AM- 11PM
INR 500 For Two
2. Sagar Ratna Restaurant
Near the Bus Stand, Katra
South-Indian
10AM- 10PM
INR 500 For Two
3. Mahduban
Near Main Chowk, Hotel Chinar, Jammu Road, Katra 182301, India
Indian, Chinese, Continental
8AM- 10:30PM
INR 500 For Two
4. Prem Vaishno Dhaba
Main Bazar, Katra Vaishno Devi, Katra 182301, India