get some poison resistance may be. Destroy the eggs, you can snipe them with a bow without triggering combat. Drop that thing into the Underdark. On my last run my ranger actually managed to destroy the web both he and the spider mama were standing, both falling down and taking damage. That damage seems to be a % of your total hit points, meaning the mama spider was hit for 40hp+ while he was hit for like 12, a couple of hits after that and it was a victory.
