Recovering an old account I don't have all of the info for

I used my mothers xbox live account since I was a child and didn't really think about asking for the account info before she died and haven't been able to get back in for a few years and was wondering if there were a way to recover it without the email or phone number that was attached its an old account and hasn't been accessed in a long time and for sentimental reasons want it back but I guess I understand if thats not possible I have the email and password that is about it

I have no way to login to the emails because she would regularly change the passwords and forget them herself
The phone is LONG gone
I wont be able to answer the childhood friend security question which I was prompted I do not know if it changes I only tried once

:)