If Maria was confused/lost, it makes sense that she went to the restaurant. Perhaps she drove past it and recognized it.
If she was not lost, then why park so far away from where she was going? I guess you would do that if you didn't want anyone to know that you went to a certain place. That place could have been a meet up location. Or, perhaps she was up to something sinister. What if she was carrying a gun? What if she tried to use it and was overpowered by someone?
I just throwing things out there. Nothing makes any sense in this case. If she wasn't actively hiding or abducted/killed, one would expect her to turn up somewhere.