Highway 49 from Jackson to about the middle of Covington county (Collins) is mostly clear in both directions. There's was an impass southbound for about two miles yesterday, but the national guard was cutting through it as I passed by. When there was an impass, people drove on the opposite side of the highway like a two-laner, although enough people have probably worked to improve the situation since then. If you choose to go, go slowly because the way cut through is often just narrow enough for a single car to pass through carefully at five miles an hour.
Hardy street seemed mostly clear and drive-able. During the day, cops/men were directing traffic through the larger intersections. Trees are down across the street in every neighborhood. Many industrious neighbors have cut paths through for cars, although there is no guarantee for specific areas. Fortieth Avenue is also passable, albeit difficult. If you absolutely must get down there, at the very least you can drive down Hwy49 then drive down Hardy and walk the rest of the way to your house. It is likely that a way has been cut through your neighborhood if you live in the city.
The best source of local, specific, helpful information is Mississippi Public Radio, not national news services like CNN. CNN is reporting on the more dramatic destruction on the coast and New Orleans. MPR is reporting on all conditions around the state including boil water notices, travel, utilities, and supplies. Listen online before you leave, and just keep scanning the lower end of the dial as you drive. You should be able to pick up at least one frequency throughout the entire state.
If you go down there, you will very likely not be able to buy gas for a return trip. Take enough food and water for at least two weeks. If you want to be helpful to yourself and your neighbors around you, take hand tools like hand axes, fire axes, hammers, nails, saws, screwdrivers, screws and gas-powered tools along with lots of fuel. Take work gloves, sunscreen, a hat, tarps, and towels.
There will very likely be no power, water, or telephone connections at least until the end of the week, perhaps into late next week or longer.
Honestly there is little to no rescuing to be done in Hattiesburg, and going down there is strictly for the sake of returning property and life back to normal. As hard as it is to say, please don't worry about your family. Only those who were driving around during the storm or refused to leave their mobile home were at fatal risk. It's only until you get within fifteen miles of the gulf coast that loss of life becomes a serious concern.
If you have a pet that has been left untended, that's a personal call. My cat, Izzy, is like my child, so I would make that trip down carrying as much gas as I needed. There are some cell lines still open in town, so if you can get a hold of someone to check on them, try that first.
Whatever you do, if you decide to go down to Hattiesburg now instead of waiting until the roads are "officially" open, please be careful, carry what you need to survive plus extra, and stay out of the way of emergency workers/vehicles. Do not go further south to the coast, unless you are part of an organized relief group. You'll just get in the way and deplete valuable resources.
I hope this information has been helpful.