Final answer:
Lampetia is the Heliad in Nonnus's Dionysiaca who was married to the river god Hydaspes, and she was a daughter of Helios.
Step-by-step explanation:
In Nonnus's Dionysiaca, the Heliad you are referring to is Lampetia. She was one of the daughters of Helios, either by Clymene or Ceto. In the Dionysiaca, Lampetia is described as being married to the river god Hydaspes. The Heliades, of which Lampetia is a member, were the nymphs of the sun, often associated with the mythological stories involving Helios, who is the personification of the sun in Greek mythology.