Have the druid cast "protection from poison" or "Lesser Restoration" on everyone. If he doesn't have either readied then he needs effectively take a long rest and ready one of them. At lv 5 he has 5 uses of either(3 lv 2 slots and 2 lv 3 slots).
You touch a creature and can end either one disease or one condition
afflicting it. The condition can be blinded, deafened, paralyzed, or
Protection from Poison
You touch a creature. If it is poisoned, you neutralize the poison. If
more than one poison afflicts the target, you neutralize one poison
that you know is present, or you neutralize one at random.
For the duration, the target has advantage on saving throws against
being poisoned, and it has resistance to poison damage.
Based on the 1st sentence this is a venom induced paralysis, and thus should be covered by both spells. If you have a party of more than 6 people(including the druid) this will take you 16 hours to heal everyone, unless you got another caster with aforementioned spell options. If you heal the mentioned ranger first, he too should be able to cast either spell.
Now if the paralysis is caused by more magical means then you want "Dispell Magic", a 3rd level spell.
Choose any creature, object, or magical effect within range. Any spell
of 3rd level or lower on the target ends. For each spell of 4th level
or higher on the target, make an ability check using your spellcasting
ability. The DC equals 10 + the spell’s level. On a successful check,
the spell ends
That would be 2 uses per 8 hours of rest. Since your DM has assured you it ain't a TPK yet, Ima assume it is non magical venom.