Signifies change in title/ownership by transfer in land/revenue/land records of authority under whose jurisdiction property falls.
In your case IT is DDA.
DDA acquired the land and launched the scheme.
Your father applied and got the said plot by allotment and allotment letter was issued and possession of said plot was given.
Your father preferred to relinquish the said plot in the name of your mother by RD (believing that RD was an accepted mode by DDA) and since IT was accepted mode of transfer by DDA, the title was transferred in your mother’s name.
Since your mother was title holder she could sign (registered) gift deed in your favor.
If IT was registered gift deed then you could submit the same to DDA for updating in records transfer the title in your name.
Has the said plot been transferred in your name by DDA?
If yes, you are tile owner.
Is your name reflected in the records of DDA?
If not, then why you have not got IT done?
If not, get IT done.
If you have got IT done then what is left for the said purpose of mutations and what is your doubt?
If you have not got IT done then is IT due to nonpayment of some charges say;Non Construction charges? If yes, DDA may have provisions to recover the charges, levy penalties and/or even resume per procedure…. Check with DDA.