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, she or he is automatically agreeing to that clause.
In case the transfer creates any problem to the employee on health , personal or environmental ground, a request can be raised by the employee with its HR .
There is no hard and fast rule that such requests would to be catered, but depending on the criticality, variations would be offered. Negotiations are entertained if the employee have to work under certain hazardous condition, with lesser infrastructure and support or an expensive location.
City allowances are offered, when transferred to a place with an higher Living Index. Family support with child's education and residential offers are made when relocating to a remote location.
Hope that answers your question.