To help Shally grow her snack business, she can consider adding the following items to her menu:

1. Mandazi: A popular fried dough snack that goes well with coffee.
2. Chapati wraps: Filled with various ingredients like vegetables, meat, or eggs.
3. Bhajia: Deep-fried potato, cassava, or vegetable fritters.
4. Roasted maize: A simple and popular snack option.
5. Fresh fruit salad: A healthy and refreshing choice for customers seeking lighter options.

Additionally, Shally could offer combo deals or meal packages to attract more customers. It's also essential for her to focus on customer service, marketing, and possibly exploring delivery or catering services to reach a wider audience. Conducting surveys or gathering feedback from customers can provide valuable insights into what they would like to see on the menu.