why there are no more momand pop stores in small towns?

Answer 1

Because large retailers drove them out of business.

Answer 2

Mom and pop shops are no longer in business, because they could not compete with large retail stores. They needed to make a higher percentage of of profit on their goods because they were selling less. Thus they had higher prices, and people went to the lower priced stores. They also could not offer all the services, selection of goods, and technology that larger stores could afford, so people shopped at larger stores for convenience.