It doesn't matter whether or not you touched the funds, the basis is still the fair market value of the shares owned on the date of your mother's passing in 2023.
Any shares that were acquired, in any manner, after that date have a new basis, which would be the value (purchase price or otherwise) on the date they were acquired.
So, you need to keep records of the FMV of the shares owned as of the date of your mother's passing and also the shares acquired (purchased and reinvested) after that date. Also, any shares that have not been held for longer than 1 year are short-term.
