How to manage database for multi company register in The Same App (Only One)?

I try to crate and deploy Restaurant App online.
App has Register Form to allow nay use want to use.
So it mean that have many company register in One App

// Ex
- UserName
- Password
- Company Name
- Address

How to solve to manage database:

1- Create new db name with one company registered (company_a). And allways config DB Name on Meteor when user login.

2- Use only one database for all company register, but use Company Id Field of Collection to manage data of each company

// Ex
Customer Collection = {
  companyId: '01'

Please help me