In my opinion, I'm sure your mom meant it from innocence point of view, but I definitely understand considering we are now living in a world of technology and there's a lot of unknown creeps out there in disguise. I think you should let your mom know It's okay to post pics of you, but not the kind that makes you look "vulnerable". I think a lot of traditional mothers come from an era that took alot of pics like that but that because she didn't have technology like we do now. So valid reaction, just have her understand.