The correct answer is había.
The verb HABER in Spanish is used to denote meanings such as "There is" or in the past "There was" something. Here, the sentence means - When I went to the "El Rancho" supermarket, there were always a lot of people waiting to buy meat.
When used with this meaning, the verb HABER has only two forms - HAY for present and HABIA for past. Habian and hubo are incorrect forms.
