Is a mother who died due to an organic disease that led to an esophageal blockage, preventing her from eating and drinking, and who was affected by a poor psychological state before her death, considered among those who died of an internal illness and is counted as a martyr?

The "mabtūn" (one who dies of an internal disease) is someone afflicted with a stomach illness such as diarrhea or dropsy, or anyone who dies from a disease in their abdomen, generally speaking. Accordingly, your mother is not considered among them. However, if one sincerely asks Allah for martyrdom, Allah may grant them the status of martyrs, even if they die in their bed, based on the Prophet's (peace be upon him) saying: "Whoever sincerely asks Allah for martyrdom, Allah will make him reach the status of the martyrs, even if he dies in his bed."