Like the previous reply said, ball pythons don't hibernate during the winter, they go off feed for breeding season. What you want to do since yours has been outside in the elements and the cold, is keep her warm and after about a week start offering her regular sized meals again. Keep her warm (85 on the cool side) and keep an eye on her to make sure she didn't catch anything (mites or a cold or lord knows what). See if you can get her to eat whatever she was eating before she escaped, a mouse, rat, whatever. You'll probably also want to soak her to make sure she's not dehydrated from her stint outside, 3 months is a long time to be without a guaranteed source of clean water.
After a week or two you should hopefully be back to normal 
~jenny
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1.2 normal ball pythons (Cindy, Darwin, and Periscope)
0.0.1 california kingsnake (tetris)
1.0 rex rat (Scurvy)
0.1 bunny (Spazz)
1.1 betta fishes (Vicious and Killer)
2.2 great danes (Shasta, Odysseus, Merlot, and Watson)
1.0 fat fuzzy mutt (Smokey)
1.1 cats (Thidwick and Turtle)
2.0 horses (Buddy and Sam)
1.0 goat (Billy Jack)
1.25 chickens (Ugly the rooster and his harem)
"God is a comedian playing to an audience too afraid to laugh." - Voltaire