#thelepassa

Apollodorus, Library:

On the disappearance of Europa her father Agenor sent out his sons in search of her, telling them not to return until they had found Europa. With them her mother, Telephassa, and Thasus, son of Poseidon, or according to Pherecydes, of Cilix, went forth in search of her. But when, after diligent search, they could not find Europa, they gave up the thought of returning home, and took up their abode in divers places; Phoenix settled in Phoenicia; Cilix settled near Phoenicia, and all the country subject to himself near the river Pyramus he called Cilicia; and Cadmus and Telephassa took up their abode in Thrace and in like manner Thasus founded a city Thasus in an island off Thrace and dwelt there.

When Telephassa died, Cadmus buried her, and after being hospitably received by the Thracians he came to Delphi to inquire about Europa. The god told him not to trouble about Europa, but to be guided by a cow, and to found a city wherever she should fall down for weariness. After receiving such an oracle he journeyed through Phocis; then falling in with a cow among the herds of Pelagon, he followed it behind.

We're never told about how much time did his journey last, nor how many years did he live in Thrace. And the fact that he went to Delphi after his mother died leads to many possibilities:

1) Telephassa's health worsened after Europa got kidnapped, which is why she decided to accompany her sons throughout their journey in the hope that they'll manage to rescue her. The fact that she remained in the end with Cadmus means that her other two sons gave up much earlier than him.

2) Cadmus settled to Thrace partly because he knew his mother will soon pass away and wanted to give her a proper burial;

3) Either Thelepassa asked Cadmus to search for Europa again or Cadmus decided to do that himself, knowing that his mother died without seeing her daughter again.