Dear Manish
Since your mother is a Government Employee, she is bound by the Terms & Conditions (T&C) of her employment with the concerned Department.
You check the T&C of her employment. In case, if the same does not permit her to visit other place you can question the Doctor's instructions.
You can also get initiated departmental proceedings against the Erring Officials / Higherups.
Before taking any step, you check and confirm the same.