The owner of the condo owes the money. Unless he entered into an agreement where the option-holder pays the dues (that obviously didn't happen here since you say that "no one is taking responsibility".
The option-holder has not "bought" the condo until she exercises her option (usually by paying more money). If she exercised her option in April, she owes the dues from April. The previous owner owes for March and earlier.
Sep 16, 2011