You will need to file an IRS form 982. The form indicates that your father was insolvent prior to the cancellation of debt, therefore the 1095-C income is excluded from taxation.
https://www.irs.gov/pub/irs-pdf/p4681.pdf
The following TurboTax link will walk you through the steps:
https://ttlc.intuit.com/questions/3473409-how-to-file-form-982
