TL;dr - if you want to maintain intra-party balance, hand out items that fall into a single category.
So, if you want to make sure you maintain balance within the party, there are, fundamentally, 2 solutions.
The first, and easiest, is not to give anyone magic items.
This is an option that 5e totally supports, and your party in particular won't be too disadvantaged by it. This is because the only reason a party starts to really need magic items at high levels is because the monsters start having resistance (or even immunity!) to non-magical weapon attacks. However, your party only includes one character for whom this will be a problem - the Rogue. The other characters all have ways around this problem. So not giving out magical items is absolutely an option.
However, magic items are awesome and shiny! And you probably wouldn't be asking this question if you didn't want to give your players some.
The second method is ...
... (somewhat obviously), to make sure the magic items you hand out allow your players to maintain parity. Note that unless you invest in some major railroading, like having items "bind" to players or something, you can't guarantee parity. If you hand out a magical item for each of them, they might decide that they're better off loading 2 characters up with everything you handed out. That's up to them, obviously; all you can do is give them items that allow them to be balanced and hope for the best.
So, to ensure that the items you hand out enable the party to stay balanced, you probably want to give out items that fall roughly into the same category. For example, I made sure that every player in my party had a magic weapon. Simple enough, if not entirely fair on spellcasters.
A DM who I play with took a rather different approach: it's a nautical campaign, so he made sure all of us had an item that allows us to be useful in water. There was a Mariner's Armour, a Ring of Swimming, Boots of Water Walking, a Cloak of the Manta Ray, and a Helm of Water Breathing. All very different items suited to different characters, but fundamentally the same bonus to each of us.
The easiest way to start would probably be to ensure that each of your characters has a magic weapon. You can pace them out a bit, because the +1 bonus won't particularly imbalance your party. If you drop each player's "favoured weapon", odds are good the appropriate character will be the one to start using it.
For the Monk, I'd recommend something like the Insignia of Claws from Hoard of the Dragon Queen: it gives unarmed strikes the usual +1 bonus to attack and damage and makes them count as magical.
The Druid is trickier, being a spellcaster. If they spend a lot of time fighting in Wild Shape, an item like the Insignia of Claws for natural attacks would work well. If they focus on spellcasting, things get really tricky, because spellcasting is fundamentally different to attacking. Something like a Pearl of Power that provides a minor bonus to spellcasting could work.
Going forward, you want to keep giving them all roughly similar bonuses. The obvious next step for me would be AC-boosting items. Like the weapons, most players will have a particular armour type they prefer to use, so dropping a magical armour of that type should make sure it goes to the right person. For the Monk you'll probably want something like the Bracers of Unarmoured Defense.
One final final note: This answer is based solely around the principle of intra-party balance. You will need to adjust encounter balance based on how many items you hand out and how powerful they are.