Answer: No, Amanda's restaurant is not a monopoly.
Explanation:
What is a monopoly?
Definition: a monopoly is a business that is the only one selling a unique product in the market. Underline a UNIQUE PRODUCT which means it is a product that can not be easily substituted by another product in that market.
Usually Monopoly businesses hold much high confidential information about the business that is not easily accessible to other businesses such as government licence.
The products sold by the other restaurants next to her are a good substitute of hamburger if supposedly Amanda were to raise the Hamburger price ,it would be easy for people to leave her hamburgers and go for pizza or tacos from the other restaurants.