You will need to add Form 1310, which is used to establish you as your husband's personal representative. As long as the Social Security Administration has already been notified of the taxpayer's death, you can proceed with the filing. Click here for: Can I e-file a tax return for someone who is deceased?
You do not need to attach a death certificate to the tax return. Instead, keep it for your records and provide it if requested.
It depends on your specific state what form would be required. I recommend checking with the state individual income tax filing instructions. Some states would require a certificate showing your appointment, while other states have their own Form 1310, for example.
Click the link to find out How do I contact my state Department of Revenue?
Form 1310 is needed for the federal filing when you are identifying yourself as the personal representative.
Our condolences for your loss.