From the evil one (apo tou ponhrou). The ablative case in the Greek obscures the gender. We have no way of knowing whether it is o ponhro (the evil one) or to ponhron (the evil thing). And if it is masculine and so o ponhro, it can either refer to the devil as the Evil One par excellence or the evil man whoever he may be who seeks to do us ill. The word ponhro has a curious history coming from pono (toil) and ponew (to work). It reflects the idea either that work is bad or that this particular work is bad and so the bad idea drives out the good in work or toil, an example of human depravity surely.
The Doxology is placed in the margin of the Revised Version. It is wanting in the oldest and best Greek manuscripts. The earliest forms vary very much, some shorter, some longer than the one in the Authorized Version. The use of a doxology arose when this prayer began to be used as a liturgy to be recited or to be chanted in public worship. It was not an original part of the Model Prayer as given by Jesus.