Theory:

Narrator: Mother Wolf threw herself down panting among the cubs, and Father Wolf said to her gravely.

Father Wolf: Shere Khan speaks this much truth. The cub must be shown to the Pack. Will you still keep him, Mother?

Mother Wolf: Keep him! (She gasps) He came naked, by night, alone and very hungry; yet he was not afraid! Look, he has pushed one of my babes to one side already. And that lame butcher would have killed him and would have run off to the Waingunga while the villagers here hunted through all our lairs in revenge! Keep him? Assuredly I will keep him.

Lie still, little frog. O you Mowgli – for Mowgli the Frog I will call you – the time will come when you will hunt Shere Khan as he has hunted you.
Explanation:
 
Though Mother Wolf stood against Shere Khan, she was also afraid of him. Because, soon after Shere Khan left, she fell on the floor panting.

Though Shere Khan was despicable, he was also speaking the truth where the decision of the Pack was considered. The Man's cub must indeed be shown to the Pack, said Father Wolf gravely to Mother Wolf as she was down panting among the cubs.

The Law of the Jungle declares firmly that every wolf should take his cubs to the Pack Council as soon as they are old enough to stand on their own. The council is normally held once a month on the full moon. The practice is maintained so that the other wolves may accept the cubs. After the inspection, the cubs are free to roam around and are safe from other wolves until they are old enough and have killed their first buck. Until then, the cubs are in complete protection. No explanation will be tolerated if one of them is killed by a grown wolf from the Pack before attaining maturity. The punishment will be death once the killer is found.
 
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A Pack Council being held during the full moon

Hence, bringing the Man's cub to the council may turn out to be a blessing to the wolves. However, it was highly risky as the chances of the boy getting accepted by the Pack were very thin. The boy would more likely end up in danger, and Father and Mother Wolf might have to fight against the Pack.

Considering the odds, Father Wolf asked Mother Wolf whether she would want to keep the boy. Mother Wolf made her stance clear. No matter what, she would not let him go. The boy came by night, all naked, alone, and hungry. Yet, he was brave and unafraid. The Mother pointed out how the boy had pushed one of the cubs already.
 
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Mother Wolf wants to raise the boy along with her cubs
  
Moreover, had Shere Khan killed the boy, the villagers would have hunted the hills in revenge. Shere Khan, on the other hand, would have run back to Waingunga. Hence, Mother Wolf was determined to keep the Man's cub.

Later, she addressed the little boy for the first time since his arrival. She called him 'little frog' and comforted him by asking him to lie still and at ease. She named him Mowgli the Frog. The boy reminded the wolves of a frog as he didn't have any fur and could not lie still. The play ends where Mother Wolf took a wow that there would come a time when Mowgli would hunt Shere Khan as he had hunted him.
 
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'The time will come when Mowgli will hunt Shere Khan', says Mother
 
Meanings of difficult words:  
 
S.No
Words
Meanings
1
Panting Breathing with short, quick breaths
2
GravelyIn a serious or solemn manner
3
GaspsTo catch one's breath with an open mouth, due to pain or astonishment
4
BabesLittle ones or babies
5
Lame Unable to walk without difficulty as the result of an injury or illness affecting the leg or foot
6
Butcher Someone who slaughters and cuts up animals for food, esp. in a violent manner
7
Lairs A place where a wild animal, especially a fierce or dangerous one, lives
8
Assuredly Used to express the speaker's certainty that something is true; without a doubt
Reference:
State Council of Educational Research and Training (2019). Term-3 English Standard-6. The Jungle Book. (pp 116 - 121). Published by the Tamil Nadu Textbook and Educational Services Corporation.