When the taxi pulled up to the little blue house at two in the morning Mabel Walker was waiting for it out front like a good passenger.
“What a sight I must be,a n old lady getting into a cab in the wee hours wearing nothing but a night gown and a hair net.”
A young man with light brown hair got out and opened the door for her.
“What a nice fella you are. I'm Mabel Walker.”
“Arthur Ferryman Ms. Walker Pleased to meet you.”
Arthur flashed her a grin which she returned. Mabel got into the back seat. Before she had time to think of the action as odd she had buckled her seat belt.
“Tell me the truth Arthur. I'm dead aren't I?”

I presume this is an updated "boatman across the river Stynx" story (vis Arthur Ferryman), so that has me intrigued (and the end hook, "I'm dead aren't I?" is nice).

The first line of dialogue from Mabel is a real problem for me. If you intend for Mabel to be speaking to Arthur (which would paint her self-depreciating character nicely), make it clear and make sure it's physically possible (right now she's speaking to Arthur while he's still inside the car). If she's speaking to herself, it seems like dialogue intended for the reader as I can't imagine someone saying that *whole* sentence to themselves.

Some of the sentences need commas, but the more I read this opening, the more is appealed. It's very simple, but it worked for me.

regards,

Nick

The action, I assume, is buckling the seat belt and it is odd because she believes herself dead. Doesn't feel right. She probably buckles out of habit and would give it no thought regardless of whether she's dead or not. Actually, if she realizes she is dead, she may actually want to buckle, to cling to security in ultimate uncertainty despite the knowledge that it will do her no good.

Original: “What a sight I must be,a n old lady getting into a cab in the wee hours wearing nothing but a night gown and a hair net.”

For me this read too long and a little stilted. I don't know many people who would say all that in one breath, and I think the content should change a little. Maybe you could change the order of what she says is odd: is it odder that she's old, getting into a cab in the wee hours, or the way she's dressed? For me the oddest thing is how she's dressed. I'd start with her commenting on that.

Secondly, her introduction feels non-sequitir. "What a nice fella you are. I'm Mabel Walker." I think if anything the cab driver should introduce himself first. Social protocol doesn't seem to dictate anyone introducing themselves to cab drivers, even if they are "nice fellas." I think it would read better if she just commented on his manners, and after he introduces himself, she reciprocates.