The accused father has been identified as Jafar Hushain (40), while the son is a minor, North District police said.
In her complaint, the woman said that she was standing in a queue at a State Bank of India branch in Shahtri Nagar when the duo approached her and took away a part of the cash that she was carrying, by trick, police said.
Realising that some amount was missing from her cash, the victim raised an alarm, when the duo tried escaping, but were caught by passers-by.
An amount of Rs 6,500 was recovered from the son during a search, they said.
The minor accused has been sent to observation home while Hushain was arrested after interrogation, police said.