Hi! So Abu dhabi is a beautiful city with loads to do. But for one day, they should definitely go see the Sheikh Zayed mosque preferably around sunset because thats when it shines in its full glory of lighting.
Then they should definitely go check out the abu dhabi corniche with maybe a lunch at nation towers and see the emirates palace.
In case they want to check malls, there is marina mall right on the corniche which has a variety of shopping options both high end and local.
Hope that helps :)
