Would Ravi be able to keep up his promise to his mother?
No, Ravi would not be able to keep up his promise to his mother. His mother had strictly instructed him not to let Grandpa go out on his own, and Ravi had promised her that Grandpa would be fine at home with him.
However, Grandpa went out alone to the corner shop for a newspaper. Although Ravi decided to follow him secretly at a safe distance, he eventually lost track of him.
Ravi could not find Grandpa at the barber shop or the park, leaving him frantic and sick with worry. Since Grandpa went out alone and went missing, Ravi failed to keep his promise to his mother.
Explanation
Ravi promised his mother that Grandpa would be fine and that he would not let him go out alone. However, Grandpa managed to leave the house alone. While Ravi tried to follow him secretly, he lost sight of Grandpa and could not find him at the barber shop or the park. The text mentions Ravi was frantic and sick with worry, wondering if Grandpa would find his way back, which clearly indicates he was unable to keep his promise.