If the same is rental property you can take a ground of adverse possession and file a suit. But If you want to challenge you can vacate the same in good faith

1. Your status is like a tenant and even if the same was under pagdi system then also there would have been no difference.

2. A tenant always remains a tenant only and irrespective of long duration of stay as a tenant , his right never develops into any better right over the property.

3. So at any point of time the landlord can file a suit for eviction and if there is merit in the suit the suit will be followed by the decree of eviction.

You are not tenant of the premises 

2) you were allotted the house because your grandfather , father were working fir the NGO 

3) in case they are ask you to vacate and you refuse to do so eviction suit would be filed against you 

1. If they are not accepting rent then you can deposit rent in the court. In every Rent Control Act there is more often that not a provision to deposit the rent in the court.

2. Before taking the above step you should serve a notice to the landlord.

1) You have to keep watch on what is next step of NGO staff or authority are they going to start any trust or NGO and the property belongs to whom  as of now. Are they planning to give on rental to any other business etc. As of now they can't vacate you people, they have to give you proper reason behind it and than you can think on it.

It appears that the premises were allotted to your grandfather whilst he was in service of the NGO

After your grand father's death, your father continued the service and therefore the NGO extended the stay in the premises

The NGO did not give any notice asking to vacate, till now

Thus by implication they continued the authority of the family members of their deceased employees to continue to live in the premises 

This in a way establishes landlord tenant relationship

Though the NGO can take the stand that the initial entry of the employees (now deceased) was authorised but upon their demise, the family members had no right to live in the premises, as the legal heir was not taken in service, and thus their presence in the premises became unauthorised and a trespass for which the NGO has a recurring cause of action for each day that the family members continue to stay in the premises and thus NGO's inaction wont be affected by law of limitation 

This is the possible stand the NGO can take

As the NGO has not taken out any eviction suit against you as of yet, you can file a declaratory suit in rent court to declare you as tenant and claim tenancy of the premises be transferred to your name

See you should pay regular rent to be in possession of you are not paying rent they can take steps to.evict you. 

If the land lord has stopped taking rent then that can be used as defence if they go for any suit. As there is no demand of rent also all these years.

Once a tenant always a tenant is the normal norm.
However you can deposit rent in court by filing a simple petition in Rent Controller Court. This should clear your intentions as a tenant. 
You can further file case against the owners (new) to restore the property for basic needs such as water,shed and electricity.
You should never default in payment of the rent.

Dear Sir,

The following information may kindly be read;

The Rent Control Act offers security of tenure to the tenants and restricts the landlords’ power to evict tenants.

Tenancy refers to the possession or occupancy of lands, buildings or other property by title through a lease or on payment of rent. The two types of tenancy agreements in India are:

• Lease Agreements which are covered by rent control laws and;
• Lease and License Agreement which are not covered by rent control laws

The rights of a tenant are :-

1. A tenant has the right to a house that is fit to be lived in
2. The tenant is also entitled to have appropriate contact information (telephone numbers, email addresses, postal addresses, etc.) and the landlord can be contacted at any point of time
3. The tenant has the right to privacy
4. Tenant can directly deposit the rent to the credit of the landlord. If the landlord fails to respond, the rent can be sent via money order to the landlord
5. The tenant is entitled to reimbursement for any repairs that he/she carries out that are the landlord’s responsibilit
6. The tenant is entitled to a certain amount of notice of the termination of tenancy.
7. Legal heirs of the tenant are also tenants and is entitled to receive all the protection available to the tenant under the Rent Control Act
8. A tenant has the right to a copy of any register entry held by the RTB dealing with tenancy.
9. Your landlord does not possess the right to insist on continued tenancy. The tenant has a right to vacate the premises for a valid reason
10. Your landlord has no legal right to ask you to pay the rent and not settle it against the deposit during a notice period.

Hi,

If the payment of utility bills is done by the medium of online, better pay the same and keep the receipts with you. 

Eventually you don't have any right on the property at the property belongs to NGO and it was let out to your father and grandfather after the death of your grandfather and father the tendency would have been transferred in your name and you would have paid the rent well in time and without default in that case you would have right to go to the court to live in the property in case you get any Notice from the NGO to vacate the property

You would not be deemed as a tenant as per law as the said premises was allotted to your grandfather and father who used to work for the NGO.

NGO can file eviction suit against you in order to evict from the property. You do not have any rights per se to stay in the said premises. 

A tenant is always a tenant.

Since the NGO has stopped accepting rent from you it may be planning to evict you through court of law for default in rental payments.

Hence you may approach court to deposit the rent to safeguard your tenancy interests.