Theory:

     ‘No, you keep it. It’s yours.’

     ‘But it could have remained in the tree for another twenty-five years if you hadn’t climbed up to look for it.’

     ‘But if you hadn’t come back again....’

     ‘On the right day, at the right time, and with the right person’, he said, getting up and placing the medal in her hands. ‘It wasn’t the Cross I came for. It was my youth.’

     She didn’t understand that, but she walked with him to the gate, Where the road turned, he looked back and waved to her. Then he quickened his steps and moved briskly towards the bus stop. There was sprightliness in his step, and something cried aloud in his heart.

     The mango scented summer breeze made the blood course in his veins, and he forgot, for a moment, that he couldn’t climb trees any more....
Explanation:
 
She said that he could keep the cross as it was his.
 
He said that it would have been left in that place for another twenty-five years if it was not for her to see in that tree.
 
But what if he would not have come back to see the house.
 
On the right day, at the right time with the right person, he was enjoying with that little girl. He gave the medal to her and said that he did not come for that, only to remind himself of his youth.
 
She did not understand that as she was too young and couldn't relate to it. She just walked along with the man till the gate, and till the road turned, he waved her goodbye. He went faster towards the bus stop. There was something more; the man was more active now.
 
The air was smelling of mango tree, and he felt more happy and energetic. For a moment, he forgot that he could not climb trees anymore.
 
Meanings of difficult words:
 
Number
Word
Meanings
1.
 Sprightliness  Being energetic.
2.
 Veins Any of the tubes forming part of the blood circulation system of the body.
3.
 Briskly  In an active, quick, or energetic way.
4.
 Scented  Having a pleasant smell.
Reference:
State Council of Educational Research and Training (2018). Term-1 English Standard-9. I Can’t Climb Trees Anymore - Ruskin Bond (Slightly adapted) (pp. 157-160). Published by the Tamil Nadu Textbook and Educational Services Corporation.