My mother is being Stalked since high school

Today my mother told me that she has been getting calls from someone she barely interacted with who constantly wanted her attention after she fell from delivering some appliances to her teacher. at first i thought she was over thinking it and he just had some interest with my mother.

But then she mentioned that even after high school she constantly received letters from this guy (she didn't have a phone at the time) talking about his life and all but when ever she asked about his family he either remained silent or just refused to say anything, and she mentioned that his notes contained this particular to it (but she doesn't remember it) which made her feel un-easy.

Next thing she knew he started VISITING her almost every she either lived or worked at unannounced saying that he just wanted to "meet", and each time its him in a red car with his son who looked somewhat crippled and malnourished(i remember meeting up with them one time when they visited so i remember what that son looked).

His pursuits has even reached her phone with him sending messages try to chat, say something about him working for the United Nations in NYC (Him and my mother started of in the rural areas in Africa so it felt way too outta place). its even gotten to the point of him trying to find contact through her other past school mates every time she blocked his number, and on each number she mentioned he had that weird Red Dragon profile picture, not sure if that's relevant but ill just mention it.

The only reason i was made aware of this is because i got a random whatsapp message from a contact i have never seen asking for my moms number recently, and he even said who he was so it made it easy for her to recognise it was him. Now im getting concerned for her safety and how far this guy will go to make it to our new home. and what his intentions are