He was on his way to a meeting in Pembrokeshire when he noticed the woman dangerously close to traffic.
Coleman is said to have driven around Haverfordwest for half an hour to see if the woman could recognise her home, before calling friends in the town to ask for help.
More top news
Plaid Cymru will hear another warning today against division at a conference which has seen open discussion about its future direction.
The JFM store in Ely, Cardiff is closing down because the landlord is selling the property.
Owen Smith has been sacked from Jeremy Corbyn's shadow cabinet after calling for a new EU referendum.