How did Aisha - mother of believers - die?

There's no evidence whatsoever that she died of unnatural causes. Aisha-May Allah Be pleased at her- died 678 B.C, and most likely of natural causes. If you mean the story where Ali- May Allah dignify his face- captured her, then you're mistaken. Yes he did capture her, but refused to harm her in any means, besides she died after this incident many years later.

Aisha - wife of Muhammad - mother of believers had a natural death at Mecca. See the exerpts from wikipedia -

Aisha bint Abu Bakr was a wife of the Islamic prophet Muhammad. In Islamic writings, she is thus often referred to by the title "Mother of the Believers". She is quoted as source for many hadith (traditions about Muhammad's life), with Muhammad's personal life being the topic of most narrations.

Aisha is a controversial figure because of differing portrayals of her in Shi'a and Sunni versions of Islamic history and her role in the First Islamic civil war at the head of an army against Ali ibn Abu Talib in the Battle of Bassorah.......

.......Aisha, in the meantime, lived in Medina and made several pilgrimages to Mecca.

In 656 C.E. Uthman was killed by rebellious Muslim soldiers. The rebels then asked Ali to be the new caliph. Many reports absolve Ali of complicity in the murder. He is reported to have refused the caliphate. He agreed to rule only after his followers persisted.

Aisha raised an army which confronted Ali's army outside the city of Basra. Battle ensued and Aisha's forces were defeated. Aisha was directing her forces from a howdah on the back of a camel; this 656 battle is therefore called the Battle of the Camel.

Ali captured Aisha but declined to harm her. He sent her back to Medina under military escort. She lived a retired life until she died in approximately 678....