Wrong site but if children are his then yes she can get a certificate

Fixya does not have access to or any authority to issue documents of that type or anything else that is controlled by local authority government
try googling who issues ***** certificates in your area
Certified ***** certificates are issued to anyone who has the fee required to prove that the person has been registered as legally dead for legal or financial purposes
the issue of the certificate doesn't need your permission as the record belongs to the state (county ,state ,country ) authority and is available to anyone who asks
this is a help site