For your mother if you dont use the Smart transit hotel, the Radisson is the best choice She will also be picked up by a uniformed driver with a signboard bearing her name who will speak English The hotel is a 1-10min drive from the terminal It is a fully equipped 5 star. Full international buffet breakfast normally included or room service on payment Pool..gym... multilingual staff....etc...
By the way standards in top end hotels in India (all brands) are way better than in Europe or the US Expect more not less