Theory:

     “He can’t be poor if he’s a crook on the run,” I told him. “He’s probably got millions of rupees stashed away somewhere in that room.”

      “Do you really think he’s a criminal, Maya? He doesn’t look like one,” Nishad looked doubtful.

     “Of course he’s one, Seven,” I said, “and he certainly isn’t starving. Mr Mehta told us that Ramesh brings his meals up from the restaurant downstairs.”

     “But Maya, Mr Mehta told us he doesn’t work anywhere, so how can he possibly have money to pay for food?” Nishad said.

     “Exactly!” I exclaimed. “He must have lots of money hidden somewhere, maybe in that trunk in his room. It’s probably full of silver and gold and jewels and...”
     “What rubbish,” Nishad interrupted.
Explanation:
 
To recall, we saw how Nishad commented that Mr Nath didn't appear to be a crook. He also mentioned that he looked skinny and was worried that he didn't have enough money to pay for his food.
 
In the second paragraph and those which follows, we see that the siblings put forward various theories and supporting arguments. To begin with, Maya rebukes Nishad's observation and rules out the idea that Mr Nath is poor. She believes that Mr Nath keeps a large sum of money somewhere in his room. She assures Nishad that Mr Nath was not starving, and she reminds him that Mr Nath had Ramesh bring him food from the restaurant downstairs. The last-mentioned information was given to them by a man called Mr Mehta.
 
The identity of Mr Mehta (the source of information) and Ramesh (the one who delivers Mr Nath's food) is unclear. However, it is safe to assume that Ramesh is probably a worker from the restaurant as he regularly delivers Mr Nath's food. Moreover, unlike Mr Nath and Mr Mehta, Ramesh is addressed through his first name without any title- as titles are often considered a sign of courtesy or respect. Hence, it is possible that Ramesh is a skilled labourer from the restaurant. Mr Mehta, on the other hand, could be a neighbour of Mr Nath and the kids.
 
Back to the story, Nishad explains why he believes Mr Nath is starving. He reminds Maya that, according to the information provided by Mr Mehta, Mr Nath did not go for any kind of work. Hence, Nishad argues that Mr Nath is poor and is unable to provide for himself.
 
Though Nishad has a point, Maya is quick to retort by reminding her brother that Mr Mehta had also told them how Mr Nath gets his food from the restaurant. Hence, if Mr Nath was jobless, then how did he pay for his food? She later speculates that he must have a large sum of money hidden someplace, perhaps in his trunk. She also supposes that the trunk is most likely brimming with silver, gold, diamonds, and all kinds of valuables.
 
luggage-3400722_1920.png
A Trunk
 
Despite Maya's arguments, Nishad remains skeptical and rejects her theories as "rubbish".
 
From the paragraphs, it is evident that Nishad is sympathetic to Mr Nath's situation, while Maya is suspicious of Mr Nath's true identity. The stands that the kids have taken mirrors the age-old battle between heart and brain.
 
burglar-157142_1280.png
Was Mr Nath a crook on the run?
 
Meanings of difficult words from the paragraphs:
  
Sl. No.
Words
Meanings
1
CrookSeek to harm, intimidate, or coerce someone or something perceived as vulnerable
2
On the runSomething that happens after something in time; following
3
MillionDecline or deteriorate physically, mentally, or morally
4
Stash
Fall suddenly, clumsily, or headlong
5
CriminalExcited or elated by something
6
Starving
Time -12.45
7
TrunkOf a person's hair, clothes, or appearance which is untidy or disordered
8
RubbishTo reject as worthless or useless
9
InterruptTo stop someone from speaking by saying or doing something
Reference:
National Council of Educational Research and Training (2007). Honeycomb. Expert Detectives:Sharada Dwivedi (pp. 126-132). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.