Hi Athulya! The best place to explore Delhi street food is Old Delhi and Chandini Chowk. You won't find a better place to taste all the different types of food specialties. You can refer to these interesting trips for full details and more options! You do not need a guide and will have more fun exploring on your own. Most areas are completely safe for women, but you may want to avoid going to Old Delhi alone late at night.
If you want to have non vegetarian then you must visit jail road tilak nagar you will get the best non vegetarian food over there moreon if you prefer vegetarian food then you can visit sarojni nagar, chandni chowk.