Это должно быть примерно так:
import collections
import itertools
data = [
('Emp1', 'Absent'),
('Emp1', 'Absent'),
('Emp1', 'Present'),
('Emp2', 'Present'),
('Emp2', 'Present'),
('Emp2', 'Absent'),
('Emp2', 'Present'),
('Emp2', 'Absent'),
]
sorted_data = sorted(data, key = lambda x: (x[0], x[1])) # sort our data
employees = collections.defaultdict(dict)
# group by employee
for employee, employee_group in itertools.groupby(sorted_data, lambda item: item[0]):
# group by category
for category, category_group in itertools.groupby(employee_group, lambda item: item[1]):
employees[employee][category] = sum(1 for _ in category_group)
print('employees', employees) # employees defaultdict(<class 'dict'>, {'Emp1': {'Absent': 2, 'Present': 1}, 'Emp2': {'Absent': 2, 'Present': 3}})