How do i cancel yahoo account my husband passed away last september and emails are still coming?

This is how to close your account: https://help.yahoo.com/kb/SLN2044.html

Here's the information you asked about:

Requesting to close the account
To process this kind of request, Yahoo requires specific documentation:

-A letter containing your request and stating the Yahoo ID of the deceased
-A copy of a document appointing the requesting party as the personal representative or executor of the estate of the deceased
-A copy of the death certificate of the Yahoo account holder

Sending options
Please send the requested information to Yahoo at the following address:

Concierge Executive Escalations
Yahoo Inc.
5250 NE Elam Young Parkway
Hillsboro, OR 97124