My m-i-l had a load of falls when she was alive and my 6ft 2" husband and his 6ft 4" brick shithouse brother couldn't lift her between them (she was a lump though). It is, by far, the safest thing for her and you, for you to call an ambulance to get her up. Not only do they have special kit and techniques to get her up again, but you dont know what shes done on the way down or on impact. She'd need proper assessment by qualified individuals, especially when she's back on her feet - not hauling to her feet and dusting down. Especially if, like in the UK, the ambulance takes in excess of 6 hours to get to her. Plus a downed person is a dead weight, so tell your family this Internet stranger says you did exactly the right thing.