advice needed

i have an extra ordinary situation here that is hurting me.i have a neighbors duaghter who is 26 and she is not all there mentally and when she looks at me she runs like crazy t ogive me a hug and asks me when are we going to get married.i have never come on to this girl the most i ever done was buy her ice cream along with my grandchildren this summer from the ice cream truck.she is a very pretty thing i mean a knock out and i am not going to take advantage of her.i have been happily married for a long time and havent strayed.what should i do i have talked to her dad and he is confused as much as me.they have tried to ralk to her but that didnt help.any suggestions