Neighbour ask my son to bring tobacco

This is a very serious issue and an offence. 

You lodge a criminal complaint against the neighbor immediately and make sure a FIR is registered to make them alright. 

Police lodged complain and still investigating and asking for witness. But that time only criminal boy and my son was there so is my son's alone verbal evidence is sufficient to arrest him ?

"30 years old boy neighbour ................."  30 yeara old person is not a boy, but an adult person. Why his parents need to be involved?

The posting suggests deeper issues. Please post complete facts.

First of all i strictly explained it to the 30 years old neighbour boy(divorced), i told him that you are asking for Gutkha/PanMashala from my 9 years old son. If he doesn't bring it then you are leaving the dog behind. 

Boy was very aggressive and alcoholic, he did not want to understand anything, he want to only fight then i rang his doorbell then his parents came out and instead of trying to understand, they just fought and use abuse words. His mother is also alcoholic and eat tobacco.

You may lodge complaint against the the so called "30 tear old neighbour boy" with the Police. They will take care of the offences to charged.

The boy has not been arrested yet

It appears that you are pursuing prejudices than a remedy. Police cannot arrest a person at the whims of the complainant. There are bound by the due process.

On the same day I lodged my complaint (not FIR) at the police station, the police had appointed an EO for my case, the message of which had come on my mobile from the CCTNS website.

1. How was this possible because I have heard that no investigation officer is appointed in a simple NCR/ complaint without a magistrate ?

2. EO is investigating my case instead of IO. Who is EO ?

3. The police is not doing anything on this issue since last one month, so should I wait for this matter so that police forward this case to magistrate or file a case seperately with the judicial magistrate (cjm) in lower court through an advocate ?

In case you are sikh the matter becomes much more than assault by dogs.

if uou feel undue delay by police then give applicaipn to Ilaqa Magisrate.

I can simply give application to judicial magistrate or need to hire advocate to file application in judicial court ?