get my mother's money from the Bank which does not accept her WILL and document sign in Bank
You can immediately withdraw the money only on condition you are the co-owner of the account. The other way is to withdraw it step by step from ATMs with a debit card until the bank learns about the account holder`s death and blocks the access to it. .
If you were only authorised by your mom to use the account, it is not enough for the bank when it learnt about her death. They need the court ruling.