I know there are a few people where who like their Scottish holidays and I would like some help finding a nice place for a weekend away for me and the misses.

I currently live in Glasgow and only have the use of public transport, so I need somewhere I can get to from a station.
Either West coast of Highland area.
Nice scenery and countryside.
A little B&B or inn would be perfect.
About 3 hours train journey maximum (don't want to spend the whole weekend travelling)
Sadly no bikes (they have been banned)
Would like to do a bit of walking and just have a relaxing weekend.
Budget would be £100ish for the both us.

Any help would be greatly appreciated.

Morar/Arisaig area should fit the bill.

When are you going? Next week I'm off to Morar, easily reachable from Weegie land by one of the Great Train Journeys (Ft William – Mallaig line).
Single person in ensuite B&B is £30/night. I can report back if you like – will be walking, possibly kayaking on Lockh Morar.
You might want to check out some of the places on Knoydart – start with the Old Forge Inn at inverie which has links to accomodation
Apart from walking, there isn't much to do, but it's one of the best places to be doing nothing.

Moulin Inn – Pitlochry.

Good walking – Ben Vrackie walk starts from the Inn.

Train to Inverness,Bus to Durness – Loads of options for walking/B+B/dining etc.Go to Cape wrath on the bus/bird watch or if thats too far – Ullapool.Loads of hills in the vicinity and good transport.

Train to Inverness,Bus to Durness

I think that'll take a fair bit more than 3-hours travel time though. Normally I'd recommend the Gairloch area but that'd also be a fair bit more than 3 hours on public transport.

The Arisaig area sounds like a good option to me, but I'd also consider the Rannoch Station Hotel.