I'm in a sticky situation and I need advice and help.

I have a few questions. Does anyone know the laws of Pennsylvania if it is illegal to allow a elderly dementia person alone in a running or not running vehicle for a possible time span of 15 minutes to 2 hours?

Also, does anyone know who exactly would be held liable in the event that said dementia person while alone in the vehicle should happen to wander away from the vehicle and get hit OR if some how that same dementia person fooled around with the vehicle to make it move and the moving vehicle would hit and damage someone else's vehicle or injure or kill another person OR if the vehicle that the dementia person was in had a malfunction and while the driver was in a grocery store the vehicle either filled with carbon monoxide or caught on fire? Who all would be liable besides the person that drove that dementia person to the store? Would her POA's be held liable too, although they don't live close to her?

I'm desperately seeking answers. Please help me. Thank you in advance.