My mother has recently passed away, and

Rob,Certainly you need a notary - and it is also not necessary for you to be present - maybe you can give a proxy to a person you trust, to sign the succession report - The notary will advise you on how to do the power of attorney - try to see this list, of notaries who speak English, if you find one, with the office near the propertyhttp://www.lifeinitaly.it/Servizi_Immobiliari/avvocati-e-notai.php

Did your mother leave a will leaving her 50% to your father?  If so the will must be published in Italy by a notary before the succession can be done.  If there is no will then Italian law will prevail and the 50% ofyour mother will be divided between her husband and her children.     A notary is certainly the easiest way to go to sort out the succession and change of title.