Once cancer's in the brain, it's usually not curable.
Extension of life is usually not possible, except in very rare situations.

There's no point in continuing treatment, if your mother's not going to be
cured or her life will not be extended.
One has to be careful what one asks for.

We don't know of (sources of) financial assistance here.
Many people all over the world, cannot get medicine for cancer or other
illnesses.
You could ask her doctor if there's clinical trials in her country.
Here's one example http://www.clinicaltrials.gov/ct/gui/show/NCT00041275
I "searched" there and that seems to be the only one for cancer, in your
country and it's not her type, nor stage of cancer.
If you have plans to go to take her to another country, you would have to
talk to your emigration officials, fill in forms, await approval. I don't
know anything about that. Meantime your mother could pass away.
She needs a clinic or doctor (as Mike said) to help keep her comfortable
for her dying weeks or months. (palliative care).

We can be a source of support for you, once you accept the facts.
J