Yes, you or the executor must file a final return for the deceased. He will file MFS if that is what you want. You can file MFJ unless you remarried before the end of the year.
The IRS has a quick How Do I File a Deceased Person interactive assistant. It is very detailed and may give you additional information.
I am sorry for your loss. In addition to the tax return, these things should be done: cancel the driver's license, voting, credit cards, subscriptions, social media closed or memorialized, and notify credit bureaus.