Slouth, the following extract from drsleuth's timeline ("Taken from evidence I heard, & some from CO's book <modsnip>"):-
Australia - Australia - William Tyrrell, 3, Kendall, Nsw, 12 Sept 2014 - #52
“10:30-10:56 : FFC ran to AMS’s house, asked if saw little boy in spiderman suit? , AMS said no, suggested bus stop on Crn Benaroon Drive & Batar Creek Rd, FFC ran to bus stop , heard the “scream” , ran back to # 48 Benaroon Drive, got in FGM car & drove looking for WT, drove down Batar Ck Rd, thought he could not have gotten that far, went back to FGM house, ran inside & got her mobile phone, saw message from MFC, she ran out to driveway , just as MFC drove in & asked him “ Have you got William?” “ No , why would I have William?” . I can’t find him the FFC said. MFC took off frantically looking for William.”
Although I don't have a Media link in addition to drsleuth's timeline and relying on that alone, it appears that FM's drive had concluded with her arrival back by 10.30am.