Is the company reputable?

I want to pursue this deal but only if it works for both of us and so long as I can give her reputable information. 

And FWIW, your tone and complaints about something that should have "taken him 5 minutes" would give a pause to many other tax professionals who could be interested to take you as a client.These days, any professional can be easily checked online for reputation, unless it's someone brand new. 

Does anyone know a reliable plumber in the DC area?

Fortunately, the plumber's insurance took care of the damage.

A brokerage might have a good reputation for one aspect, but a specific office might not excel at it.

I don't know how you'd find a few gc's to interview but the permit office lists permits and the contractor is named and I bet you could ask a plumber or electrician who does rehab type work who they'd hire for their mom's house.

Can a plumber help with this?

Start by finding a real estate agent from a reputable company. 

Scope of Work:Plumbing fixtures (faucets, tub/shower kits, toilets) will be purchased and provided by Owner. Contractor is responsible for purchasing and installing all water supply, waste, vent piping connections, ho...