Which of the following statements is/are not true about privy purse?

The correct answer is (D) only.

To understand why this is the correct choice, let us analyze the statements related to the Privy Purse system in India:
(A) A privy purse was given to the Princely States.
This statement is true. During the integration of India post-independence, the princely states were offered a privy purse as a financial package in return for merging their territories with the Indian Union.
(B) It was given as an assurance that after the dissolution of princely rule, the then rulers' families would be allowed to retain certain private property and given a grant in heredity or government allowance.
This statement is true. The privy purse was constitutionally guaranteed (originally under Articles 291 and 362) to assure the rulers of erstwhile princely states that they could maintain a certain lifestyle, retain specific private properties, and receive hereditary allowances in lieu of surrendering their ruling rights.
(C) At the time of accession, there was little criticism of these privileges since integration and consolidation was the primary aim.
This statement is true. In 1947, the foremost priority for India was national unity, integration, and the prevention of balkanization. Consequently, the generous terms offered to the princes faced minimal political or public resistance at the time.
(D) Hereditary privileges were consonant with the principles of equality, social and economic justice.
This statement is not true. Granting hereditary privileges, tax-free incomes, and special status to a specific class of citizens solely based on lineage directly contradicted the democratic, egalitarian, and socialist principles of equality (Article 14), social justice, and economic justice enshrined in the Preamble and Directive Principles of the Indian Constitution. Due to this contradiction, the Privy Purse was eventually abolished by the 26^th Amendment Act of 1971.

Since the question asks for the statement that is not true, statement (D) is the only incorrect statement. Therefore, the option "(D) only" is the correct choice.