Got these answer from ZYNGA SUPPORT:
" This is R. and I will be glad to assist you today. ...
I am sorry to hear about your difficulties presented in the mission Mrs. Maria Rosa: Gold Mastery. I am daily player too and that is why I totally understand you. I would like you to know that I made the proper updates in your account and now you should be able to collect the reward for this Mission.
Allow me to share a tip with you, in order to avoid this situation to happen again. Before fighting a Boss, be sure to have your Health up to 100% of your maximum. Then, open a new tab or window and go to your Mafia Wars game. Go back to the first tab/window and start fighting the Boss. Before your health goes down to 0 move to the second tab/window and go to the hospital so your Health can be restore. Be patient because this can take some time to accomplish but this way you will not give a chance to the Boss to heal and you will be able to defeat him successfully."