I don't know what to do, and if this is normal or of she needs help.
A week ago, my mum was away from home, driving from a restaurant to a hotel. She got a bit lost and was on a pitch dark country lane. She realised there was a vehicle behind her. The vehicle overtook her and then kept braking in front of her. After a bit it suddenly stopped, blocking the road, and a man got out. Pitch dark country lane - my mum was terrified. She didn't stop (thank God) and drove up on the grass verge to get past him. He yelled something at her (she didn't hear what) as she drove past. She then drove off shaking and numb and took a turning, down an even smaller lane, panicking that she was getting herself into a dead end and that he'd follow her. She says she can't remember the drive back but thinks she may have switched off her lights so he couldn't see her. She saw him go past the entrance to the road she'd taken. She got back to the hotel and was badly shaken up.
Two days later, she drove home (a couple of hours away).
I saw her at the hotel and suggested perhaps her brake lights were out and he was trying to warn her. She's had the car checked and it's all working fine, no problems.
I just phoned her, a week later, and she was in floods of tears saying that as a result of said incident she is now terrified in her own home, scared to go out in the garden after dark. She said, 'The truth is, that man meant to murder or rape me'. I get that it's a very frightening idea.
She went to the police but they were a bit 
as she couldn't remember the make, model or colour of the car, didn't get the reg (was in a panic so understand this). She said the police 'made a fool of her' but it sounds like they were just trying to get her to entertain other possibilities (i.e. they suggested that the other driver's car was breaking down and they needed assistance).
She is adamant this person meant her harm. She said she is scared she has angered him by driving off and that he will somehow trace her and come and 'get' her. I reassured her that this is not possible. She said she keeps replaying the incident over and over in her head, that it's there as soon as she wakes up, that she can't sleep, that she wants to sell her car and move house (but can't) and that she 'doesn't want to go on living like this'. She said it several time and it sounded suicidal, but I don't think she'd kill herself. She lives alone. I do not live nearby.
Does this sound like a normal reaction to what she - an older woman - found to be a very frightening incident, or does she sound like she needs a doctor? Not that I'd persuade her to see one - but I really don't know what to do.