getting database values using get_object_or_404

get_object_or_404 will only return one object. You need get_list_or_404 as there could be multiple states for one disease:

from django.shortcuts import get_list_or_404, get_object_or_404

def option(request, disease_id, state_id):

    state = get_list_or_404(State, relevantdisease__pk=disease_id)
    disease = get_object_or_404(Disease, pk=disease_id)

    context = {'state': state, 'disease':disease }
    return render(request, "option.html", context)