There is a clause mentioned in every Employment/Appointment letter, named 'Employment at will'. It requires the employee to agree to work in the conditions and places as deputed by the company. When an employee accepts the Appointment Letter and signs it, he or she is automatically agreeing to that clause.
In case the transfer creates any problem for the employee regarding health, personal, or environmental grounds, a request can be raised by the employee with HR. There is no hard and fast rule that such requests would be catered to, but depending on the criticality, variations would be offered. Negotiations are entertained if the employee has to work under certain hazardous conditions, with less infrastructure and support, or in an expensive location.
City allowances are offered when transferred to a place with a higher Cost of Living Index. Family support with a child's education and residential offers are made when relocating to a remote location.
Hope that answers your question.