Welcome to HCM,
I have gone through details provided by you about your mother, she is having Anemia resulting from bleeding in intestines as such also Anemia of iron deficiency
we have to search for cause such as GI bleeding.
Her stool test
revealed occult blood positive, she certainly requires investigations for possible causes.
Please visit a Gastroenterologist and tests like CBC, with peripheral smear study,FBS,PPBS, Kidney functions, serum Iron
level,TIBC, serum ferritin, B12 level and Ultrasonography
of abdomen or MRI of abdomen as she is reluctant for colonoscopy
may be performed and if something is seen then colonoscopy with biopsy may be done.
There are certain tumor markers which can be done to point out possible cause.
If she is consuming analgesic for any other cause may lead to positive occult blood and Anemia.
In her age it is better to detect the pathology as early as possible.