Presumably your husband’s Yahoo email account is still configured in your Mail settings?
Settings > Mail > Accounts > [Your husband’s email account]
If the account is not present, re-add the account:
Add an email account to your iPhone, iPad, or iPod touch - Apple Support
If the account is present, be aware that in common with many other Mail providers, Yahoo now use App Passwords to secure access IMAP or POP3 mailboxes.
The Mail App on each of device, such as your iPad, may require a unique password to be generated from within the Yahoo account. This App password intentionally differs from the Yahoo account password - and can only be used to access Yahoo mail.
More information can be found here:
https://help.yahoo.com/kb/SLN27791.html