I130 submission for Father - Marriage Certificate requirement

[nageshcv]

hi,

My mother passed away a month ago and we are planning to bring my Dad to U.S. As part of I130 application process I noticed that USCIS requires marriage certificate. Given my mother passed away, will he be able to get a marriage certificate from the related office in Hyderabad? What other alternative documentation can I provide in lieu of Marriage Certificate to USCIS? Please advice?

Thank you,
Nagesh