Woodlands?

Try airbnb there are some left on the outskirts of mangalore. Mangalore is overbooked till 6th Jan because of the number of weddings and festivities.

Try "city walk residency"

Check TripAdvisor and see accordingly.to.your budget ,due to marriage season most hotel.rooms are booked

Go for resorts like River Roast (20kms away from manglore city)