If you kept the Helm of Teleportation (from the vending machine on the previous level) it can come in very handy in the fall back movement.
No-o-o-o-o-o-h! I threw it away, thinking it was junk.
The 'big' combat prior to Aunt bee's chamber only happens once. After that you'll only face 12 giant bees. Don't let your front rank attack during this combat, just let the second rank kill these 12. If you don't have any invisibility rings, try to kill the bees using only your 4th and 6th characters. I know this may be difficult.
When the Aunt Bee battle starts, retreat into the corridor to the southwest and form your combat line to limit the number of attackers. This may require delaying your invisible characters to screen the movement of the visible characters. Save your AOE spells until a targetable area gets pretty full. It can make for a long battle, but it should be winnable. After the B-Men and giant bees are killed, all that's left is to kill Aunt Bee. You can get 4 melee attackers on her if one has the Helm of Teleportation to get behind her. A fighter with high dex and strength could make good use of the fine long bow and +2 arrows found earlier. (I hope you still have the arrows.)
Or you can try a completely different strategy. Good luck!
I managed to beat Aunt Bea on second try.
I "cheated" slightly by casting Haste from scroll before taking the final step.
Then I had my Ranger (weakest of my fighter types) using the Wand of Fireballs on the group of B-Men to the left. My Cleric blocked as many as he could of the B-Men to the right, while being in position to set up backstabs for my Fighter/Thief. My F/T could have used that Helmet of Teleportation, but instead he quaffed an Invisibilty Potion to be able to sneak around the B-Men and come up on them from behind.
My Mage had already used up his Fireball and Cloud Kill spells, so he provided backup by casting a few Stinking Clouds and also setting up backstabs on the B-Men.
By the time all her minions were dead the Haste spell had expired, but I was eventually able to kill her. Wands of Missiles were more effective against her than I had thought.
So on second try I beat Aunt Bea with no losses.
My guys were level 6-7. I used four of the pregens, and they have better stats than my generated characters. You really need all the advantages you can get in this module.