The correct option is A True
An adjective clause is a group of words that contain a subject and a
verb, and it functions as an adjective that modifies a noun or a
pronoun. Adjective clauses usually begin with relative pronouns such as
who, whom, whose or a relative adverb like when, where and so on.
A
defining adjective clause gives essential information about the
noun/pronoun that it modifies, without which the meaning of the sentence
is incomplete.
A non-defining adjective clause merely gives extra
information about the noun/pronoun which isn't important to the
sentence. Also, non-defining adjective clauses are separated by commas from the rest of the sentence.
The given sentence has a non-defining adjective clause: 'who is my friend's aunt' does not add essential information about the noun, 'Mandira Bedi'.
Hence the statement is True; option A is correct and B is incorrect.