Porch Fest. Honk Parade.

Some of the local streets will be closed to traffic by that time so it would be advisable to check Nixle alerts and plan accordingly.  If the DeHart parking lot is full, the only option would be local streets that remain open.  Even then, parking may not be permitted on streets where there are performances scheduled.  Have you tried looking at the Porch Fest website or contacting the organizers?

https://www.maplewoodporchfest.com/

Park on the other side of Springfield Avenue. It’s a hassle driving around the Hilton section on porch fest day. 
She would have to be at dehart very early to get a parking spot. 

From Porch Fest

"As Maplewood Porchfest grows, our Hilton streets get packed with music lovers and we want to keep everyone safe!Here is what you need to know for a smooth, safe Sunday...Pedestrian Safety: Please stay on the sidewalks and out of the street unless you see a cone or barricade blocking traffic.Smart Parking: Please don't park in front of our Hilton porches! Utilize legal street parking and free municipal lots on Prospect St. & Hilton Ave., Springfield Ave. & Indiana St., Springfield Ave. & Yale St., or park at the DeHart Community Center. Parking in Maplewood is free, but please read the signs before you park, and look for the police signs to see where you can/ cannot park.Performer Access: Performers are welcome to pull up to your porch temporarily to load and unload their gear.Road Closures: Several Hilton streets will be blocked by barricades for pedestrian safety. Please respect these closures and do not drive past them unless you're a resident or performer.Maplewood police will be out keeping things running smoothly. If you need any assistance, reach out to the Maplewood Police Department. Let’s keep it fun, safe, and musical!"