KerrAvon's answer is good. It is not survivable and I don't see point in arguing that - the amount of explosive is just too extreme for such a close range.
But I just want to point out that you don't need that much. Do you want to damage the monster sufficiently to slow it down, or just turn it into a mist?
To just damage the monster sufficiently a mere 5-50g would be plenty. Absolutely no need to go for >500g.
If monster bites or punches or slashes or whatever with a physical contact, and is smart enough to avoid all traps (unlikely, but lets consider), but dumb enough to attack an armored person, then just use what tanks use - an active armor. When something hits the suit hard enough - suit responds by exploding that specific cell.
If monster is in direct contact, 5g will destroy that part of the monster's body, be it a claw or a tooth, and will somewhat protect the wearer, by distributing the hit on a wider area than a claw would hit. And it will be actually safe for the wearer, with some training it won't even cause shock and the person will able to continue their mission. Like attack the monster with something, or spray it with glowing paint.
If monster is more like a demon than an animal, and blowing off one of the claw won't scare it away, 50g of explosives will blow off a whole limb and damage lungs and shock for a long time. For cases when the creature is not limited by the surviving instinct this might be useful. But it will for sure make the wearer non responsive for a long time, and damage to the health is extreme. This person can survive, with loss of hearing, internal bleeding, a few fractures. But they have some chance of survivng, especially with medical help. And if there are more people than monsters, and mission is important enough, then probably it makes sense.
500g charge makes no sense at all, it is absolutely ridiculous. You can blow up a light transport with it, and harm the people inside. Or turn a monster into a pile of organic material.
Still, you will need to explain why traps don't work, and people are really good at making traps. Even if monster is transparent, it will give off IR. It will make sound as it walks, and some mines can detect the walk pattern of different entities to distinguish animals from a human for example. If monster flies, then sonars or radars will help. There is some sense if it is a short story and monsters appeared when people were unprepared, and people's weapon are not designed to detect monsters, that could explain it somewhat. But then making an active armor suit wont be on the table either.
I can see some point in it if there is lots of false targets. For example an alien city, that humans need to bring peace to, and some aliens are agressive, but others are not, and it is absolutely paramount to never attack peaceful aliens, but also be able to punish agressive aliens. That I think could explain why traps can't be used at all, but there is enough time to make active armor suite. And using smaller charges helps here too - large charge just can lead to too many casualties. Lots of false targets could also explain why ordinary weapon cant be used - stray bullet may kill a bystander. Or be useless if distance to the crowd is a few meters, and one alien from the crowd can jump to attack in a fraction of a second. An organic cave with lots of moving parts, like a large organism, could also make the use of traps almost impossible.
This could lead to development of a whole set of extremely short range weapons, tasers are common at this range, but it also could be short focus lazers, that quickly diverge the beam after a fraction of a meter of distance. Still, it can blind at much further range than it can burn, and that might be a disadvantage. Dumb but could be effective is exploding canister of a PU foam, especially with paint in it. Either it traps the monster, or allows to follow and find it. And suprisingly but plasmaguns. Plasma is very bad at pretty much everything as a weapon because it disperses so quickly, but if you want an extremely short range it is perfect. In just a meter it will turn to warm air, but before that it can cut any material on Earth. Basically I'm offering a plasma cutter, but on steroids. It can tick all the boxes, of being perfect weapon for such a case where you would want to use an exploding armor. It is short range, so it cant damage other targets, it is angry and cuts everything, it can work in impulse mode, it can have ridiculous power. As a bonus is doesnt harm its owner nearly as much.
One more point on exploding armor - you actually want to have 2 compartments of the explosive. This way you can 'direct' the explosion away from your body, towards the body you don't like. And more 'layers' - the more you can direct it away, making it a soft push for the one side, and rapid tear for the other side. Just want to point out that duct tape and grenades or mines won't work. It will have to be a very complex device, with sensors to activate faster than a human can react, with many layers of explosives. Otherwise other close range weapon are preferred.