DIN- Fathers Name

Prepare an affidavit that his father's full name is AMAR CHAND JAIN and JAINAC as appearing in PAN Card is only the abbreviated form of the same and get it notarised by a Notary Public. DIN authorities may accept it. To substantiate this,  you may attach X or XII school leaving certificate where his father name appears in full.

Or else try with any other ID proofs viz., DL, Passport, etc. If nothing is available, write father's  name as it appears in PAN Card i.e.JAINAC and get the DIN approved as the mention of father's name in abbreviated form really doesn't matter.

Also, get the corrections  made in PAN card by making an application and attaching the proof .

Agree with Ms. Jayashree.

If possible send any other id Proof... You may send passport which is id proof and residence proof as well.