Theory:

     He had been stroking and slapping Timothy for about five minutes when he found another keeper observing him with some alarm. Grandfather recognised him as the keeper who had been there when Timothy had first come to the zoo.
 
     “You remember me,” said Grandfather. “Now why don’t you transfer Timothy to another cage, away from this stupid leopard?”
 
     “But— sir —” stammered the keeper, “it is not your tiger.”
 
     “I know, I know,” said Grandfather. “I realise he is no longer mine. But you might at least take a suggestion or two from me.”
 
     “I remember your tiger very well,” said the keeper. “He died two months ago.”
 
     “Died!” exclaimed Grandfather.
 
     “Yes sir, of pneumonia. This tiger was trapped in the hills only last month, and he is very dangerous!”
 
     Grandfather could think of nothing to say. The tiger was still licking his arm, with increasing relish. Grandfather took what seemed to him an age to withdraw his hand from the cage.
 
     With his face near the tiger’s he mumbled, “Goodnight, Timothy,” and giving the keeper a scornful look, walked briskly out of the zoo.
Explanation:
 
Grandfather was so excited to see Timothy after a long time, that he could not help but spend more time with him. He keeps stroking the tiger for almost five minutes when he feels that someone is observing him. It was the same keeper who was present when grandfather had handed Timothy over to the zoo. He was looking at him with shock and surprise. Since grandfather was already protective of the tiger and wanted to complain about the leopard scaring him, he decides to discuss the issue with the keeper. He appeals to the keeper to move the tiger from the leopard that was creeping him out.
 
keeper_1236198319.jpg
Zoo keeper
 
The keeper who still has not come out of his shock initially manages to utter only a few words. He informs the grandfather that it was not his tiger. Grandfather, who was not doubtful about the situation previously, fails to understand the meaning of the keeper's words. He thinks the keeper is referring to the fact that Timothy had changed to a great extent from the time he was a cub and the time he was in the zoo. He informs the keeper that he understands the same. But the keeper's next few words unravels the twist of the plot. He discloses the fact that Timothy had died of pneumonia, two months ago. The tiger that he was stroking for so long was the one which was captured from the hills, and that he was particularly very dangerous.
 
Grandfather was shocked to the extent that he could not process what the keeper had said. He freezes on the spot, not knowing how to react. His hands were still being licked by the tiger. But the overall idea behind the licking was changed after revealing the truth. What seemed like a tiger's love towards an old master, turns out to be the excitement of a hungry tiger when he sees the meal. Grandfather still could not remove his hand from the cage as he was still processing a whole lot of information, that his beloved Timothy had died, and that he had misunderstood the intention of the new tiger.
 
grandpa_1790184647.jpg
Shocked grandfather
  
Although grandfather removes his hand after a long time, he goes closer to the cage and mumbles "goodnight Timothy" in his ear. This shows that in spite of facing himself with the harsh truth of the death of Timothy, he decides to escape from reality, by convincing himself that the keeper had made a mistake and that the ferocious tiger that had been licking his hands was indeed his beloved Timothy. He refuses to face the truth because of his love for Timothy.
 
Meaning of difficult words:
 
SI.no
Words
Meaning
1
AlarmA warning, being Scared 
2
StammerA lag or pause when one speaks
3
SuggestionAn idea
4
PneumoniaA lung disease
5
RelishEnjoy
6
WithdrawGoing back
7
MumbleTalking softly to oneself
8
ScornfulLooking with hatred
9
AppealRequest
10
BriskSteady
11
Creeping outScaring
Reference:
National Council of Educational Research and Training (2007). A Tiger in the House - Ruskin Bond (pp. 58- 65). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.