If the account was deleted then it is too late. Even then she is not allowed to transfer it.
You could try to get the account working again, as outlined in: How to delete your Apple Account - Apple Support
"What happens if I change my mind after I have requested that my account be deleted?
While your request is being processed, you can contact Apple Support [call them at a telephone number for your country --> Contact Apple Support - Apple Support ] with the unique alphanumeric access code you received, and we’ll help you cancel your request. After your account is deleted, Apple can't cancel the request, reopen your account, or restore your data."
For information about how to request access to a deceased family member's Apple account data, and possibly their equipment, read this support article --> How to request access to a deceased family member’s Apple Account - Apple Support
Legal - iCloud - Apple
IV. D. No Right of Survivorship
Except as allowed under Digital Legacy and unless otherwise required by law, you agree that your Account is non-transferable and that any rights to your Apple ID or content within your Account terminate upon your death. Upon receipt of a copy of a death certificate your Account may be terminated and all content within your Account deleted. Contact iCloud Support at iCloud - Official Apple Support for further assistance.