This question is really vague.
Should they be legally compelled to do so? God, no. Let me get 50 hamsters and treat them like shit to get days off.
Should they do it on the grounds of human decency? Yes, if they can and the grievance is real. There might be times were you cannot give an employee time off without jeopardizing the business. And it might be that the grief is really just silly. If your doggo, who spend 15 years faithfully on your side dies tragically - This must be hard, I am sorry. Take your time to get better. If you are devastated because your gold fish randomly died - I am sorry, but get a grip and do your work.