The following description from a book on Vietnam provides some information on the Mariamman temple.
Mariamman Hindu Temple, the only (?) Hindu temple still in use in Ho Chi Minh City (Saigon) is a little piece of southern India in the centre of Saigon. Though there are only 50 to 60 Hindus in Saigon - all of them Tamils - this temple, known in Vietnamese as Chua Ba Mariamman, is also considered sacred by many ethnic-Vietnamese and ethnic-Chinese. Indeed, it is reputed to have miraculous powers. The temple was built at the end of 19th century and dedicated to the Hindu Goddess Mariamman.
The lion (Simma Vahanam) to the left of the entrance used to be carried around Saigon in a street procession every autumn. In the shrine in the middle of the temple is Mariamman, flanked by her guardians - Maduraiveeran (to her left) and Pechiamman (to her right). In front of the figure of Mariamman are two lingas. Favourite offerings placed nearby often joss sticks, jasmine, lilies and gladioli. The wooden stairs, on the left as you enter the building, lead to the roof, where you'll find two colourful towers covered with innumerable figures of lions, goddesses and guardians.
After reunification in April 1975, the government took over the temple and turned part of it into a factory for joss sticks. Another section was occupied by a company producing seafood export - the seafood was dried in the sun on the roof. The whole temple is to be returned to the local Hindu community.
Mariamman Temple is only three blocks west of Ben Thanh Market, at 45 D Truong Dinh. It is open from 7 am to 7 pm daily. Take off your shoes before stepping onto the slightly raised platform.
The main deity of this temple is Goddess Mariamman, another aspect of Parvathy. As the mother of universe, Parvathy is amma and prayed as Amman. Utsapa amman is placed next to the main deity. During the festivals she is placed on the Simha vahana and taken on procession along the roads of Ho Chi Minh City.
In addition, my observations are as follows: At the outer hall, Goddess Amman’s (Parvathy) sons Ganesha and Muruga are on her right and left, respectively. The Rajagopuram of this temple is about 12m high with a number of statues. Colourful statues of Amman, Luxshmi, Ganesha, Muruga, angels and dancing girls decorate the entrance of the inner hall.
The attractive features of this temple are the beautifully sculptured Amman in her different forms as well as other deities. They are located permanently on the surround outer walls of the temple. They include Nadarajar, Param Sivam, Brahman, Mahavishnu, Kaliamma, Biramasakthi, Samundi, Thirumagal, Mageswari, Meenadchi, Valambigai, Andal, Kamadchiamman, Karumari-amman, Sivagami and Parvathy with Murugan in her lap.
Iyaaswamy Devar from Tamil Nadu is the caretaker of this temple. Devotees experienced the power of Mariamman for a number of years. Hence, this temple is most popular with the locals. This temple is now taking the necessary steps to bring a priest from India to conduct proper puja in a regular basis. I was told that with many others like Mr. Chidambaram from Tamil Nadu has shown significant interest in the temple affairs.
