class student(models.Model):
   studentNumber = models.AutoField(primary_key=True)
   studentName = models.CharField()


class hobbies(models.Model):

  studentNumber =
  models.ForeignKey(student,on_delete=models.CASCADE,blank=True,null=True)
  hobby = models.CharField()

def hobbyList(request):

   b = student.objects.all()
   c = hobbies.objects.(filter=studentNumber=n) ## here is the problem the n

   return render(request,'student/hobby.html',{'b':b,'c':c})

<ul>
 {% for n in b %}
 <li>{{ n.studentNumber }}
   <ul>
    {% for s in c %}
     <li>{{ s.hobby }}</li>
    {% endfor %}
   </ul>
 </li>
  {% endfor %}
</ul>