Cannot Reset Security Questions We don’t have sufficient information to reset your security questions.

See If you forgot the answers to your Apple ID security questions https://support.apple.com/en-us/HT201485

Given that you have been told that Apple does not have sufficient information to answer your security questions, note that

Security and your Apple ID https://support.apple.com/en-us/HT201303 says “without proof of your identity via security questions and other carefully selected criteria, Apple Support can't help you reset a password or perform any other actions on your account.”

So, given that you can't answer your security questions satisfactorily, we won't be able to help you with your problem unless you have an extenuating circumstance (e.g., you have the receipt for the purchase of the pertinent device with its serial number on it or you have a court order instructing Apple to assist in the provision of access to a decedent’s information from the deceased person's accounts). If you think you have an extenuating circumstance, even one not mentioned above, then use the support options below to get help in solving your problem. 

If pertinent, see How to request access to a deceased family member's Apple accounts https://support.apple.com/en-us/HT208510).

Get a call from Apple support to help solve her problem using this

link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362

Apple ID Support https://support.apple.com/apple-id

Apple ID account security for country-specific and region-specific help https://support.apple.com/en-us/HT204169

Get Support: We’re here to help https://getsupport.apple.com/. Go through the options to find the best support option.

contact Apple ID Support.

Apple ID - Official Apple Support.    

Contact Apple for help with Apple ID account security - Apple Support.   (Link doesn’t always load)  

Get Support          Work through the screens to get a chat option. 

https://twitter.com/AppleSupport

From the article below. 

Without proof of your identity via security questions and other carefully selected criteria, Apple Support can't help you reset a password or perform any other actions on your account. These policies are audited and reviewed on a regular basis.

Security and your Apple ID - Apple Support.