• Threatening for consequence

On Thursday 25 Jan, my mother went to a near by shop to buy few items from there. While picking up the item, she adjusted her Saree. While she was doing it, the shop keeper blamed her for theft. Since she have not taken anything, she told the the same to the shopkeeper. 
Now the shopkeeper threatened her that they will call the police. Since she have not sone anything wrong she also agreed that the police can come and check her belonging. After sometime the shopkeeper let her go. 

On 2nd Feb, when she was going to pick her grand daughter from school. The shopkeeper asked her to stop. Since, she had to pick her grand daughter, she told the shopkeeper same thing and went to school to pick her grand daughter. Mean while, she noticed that two person are following her. Most probably, they have been asked to follow her by shopkeeper. 
While returning back after picking up her grand daughter. The shop keeper stopped her and grand daughter and started accusing her for stealing a mobile phone. My mother told them that they have not taken any mobile (or anything). Later took the kid school ID card to get the parent phone number. (Most probably not in a polite manner). Once the kid parent reach the shop, the shopkeeper started telling him that the phone belong to a person, whose son have passed away and the phone contains photos of his son in it. 
When kid parent asked if they have any proof. He said they have seen it and it was recorded in the CCTV. When parent asked shopkeeper to play the recording, shop keeper said that he doesn't know how to play the recording.
Later in the evening when we went againto the shop, shopkeeper said that he have asked the customer support to come and receive the recording. 

Now coming to the question which I have
Since my mother came to visit me for few days. I'm not much worried about her as I know she can handle everything bravely. And since she have not done anything wrong, there is no point of having any fear.
The grand daughter studies in the school near the shop and usually takes the same way while coming and going to school. The kids parents (My sister and brother in law) are afraid that they might hurt the kid (mentally or emotionally). On times my brother in law, parent also go to pick and drop the kid. I'm worried that they might hurt them too.

What are the step that I can take legally. So that we are in safe hands legally. 

Tomorrow I'm going to talk to the shopkeeper to resolve the issue. But if the issue is not resolved. I don't want to face any unnecessary harassment. 

Please advice what I can do.

Thanks