Prayaga Madhaveswari is one of the 18 Shaktippethas. She is also called as Alopi mata / Lalita. Body part fell in this place: Hastanguli (Hand fingers).
Bhairava of the Shakti peeth: Bhava. Shakti: Lalitha

madhaveshvari mangalye prayagasthalavasini /
triveni sangame tire bhuktimukti pradayini //

Prayaga means Prakrishta Yaga, that means it is the place where Lord Brahma did a very great Yaga. Hence its name became Prayaga. Prayaga is considered as one of the Sapta mokshapuras. This place is also called as Theertharaj, that means king of all theerthas.
 

There are mainly three stories about the word Alopi. They are,
1)Alopi means the one who disappeared. After Sati dahana and Dhaksha Yagna destruction, Lord Siva disturbed mentally and lifted Satidevi’s body and roaming without any destination. Lord Vishnu cut Sati devi body parts by using Sudarshana Chakra. Every place, where Satidevi’s body part fell, became a Shaktipeeth. Prayaga is the last place, where last part of Sati devi’s body fell on ground. Here Sati devi body became disappeared, hence the name Alopi.
2)There are some other stories about Alopi mata. In every temple, at least one idol or one symbol will be there for worshipping the goddess. But here, there is no idol or symbol. We have to imagine the goddess present on a wooden jhula. Hence the name Alopi.
3)According to a local story, Alopi mata is a newly married bride. She disappeared from pallaki, when robbers attącked the marriage troop. As the bride disappeared as a miracle, she is worshipped as Alopi mata.