First, we are sorry for your loss.

File your 2017 return in both your names. You will still file "Married Filing Joint".

On the personal info section about your husband ("Do Any of These Apply to [name]"), be sure to check the box that he passed away before filing the return. This will exposes another line or two asking for the date of death.

This will put "Deceased" on the tax return so that the IRS knows about his passing.

Next year (i.e., for tax year 2018) you will file as single (unless you have a dependent living with you in which case you may be eligible to file as "Qualifying Widow") - but that's next year. This year, you file as if he were still with you.