Copy of any of the following document will serve as proof of address in case of individual applicants being Indian citizens (including those located outside India):

Aadhaar Card issued by the Unique Identification Authority of India
Elector's photo identity card
Driving License
Passport
Passport of the spouse
Post office passbook having address of the applicant
Latest property tax assessment order
Domicile certificate issued by the Government
Allotment letter of accommodation issued by Central or State Government of not more than three years old
Property Registration Document
Electricity Bill (not more than three months old)
Landline Telephone or Broadband connection bill (not more than three months old)
Water Bill (not more than three months old)
Consumer gas connection card or book or piped gas bill (not more than three months old)
Bank account statement or as per Note given below
Depository account statement (not more than three months old)
Credit card statement (not more than three months old)

Note: In case of an Indian citizen residing outside India, copy of Bank Account Statement in country of residence or copy of Non-resident External (NRE) bank account statements (not more than three months old) shall be the proof of address.

Alternatively, you can provide a certificate of identity in original signed by a Member of Parliament or Member of Legislative Assembly or Municipal Councillor or a Gazetted officer, or an employer certificate in original.