The Full Form of TDH is Table d’hôte.

Table d’hôte is a French loan phrase that literally means “the host’s table”. The term is used to denote a table set aside for residents of a guesthouse [fr], who presumably sit at the same table as their host.
The meaning shifted to include any meal featuring a set menu at a fixed price. The use in English is documented as early as 1617, while the later extended use, now more common, dates from the early nineteenth century.