Your mum's doc may think her body may not be strong enough to withstand more chemo. Quality of life issues may take precedence. That is where I am.
i didn't see doxil or avastin on your list of chemos. also gemzar, taxol or taxotere. all of these are used to treat OVCA, though I'm owndering if avastin was approved or is still in clinical tests. Either way though, its an option too.
take care fo your mum! make sure her wishes for her care are fulfilled (if she feels she can do more treatment, then advocate for that. if she is tired and needs a break, then advocate for that. or if she is done fighting, that then give her meaningful time, love and humor, and tell her how grateful you are...not sure where you are in the disease process, so forgive me if I'm too presumptuous).