Who do I ask for a reference after a layoff?

My manager was laid off too and I am unsure who to use as a reference. There are 10 people counting on me, so I am trying to be careful. A colleague offered to vouch for me. Is a client acceptable?

Thanks for writing this out. I went through something close to it 13 months ago, and it got easier once I kept a simple log of every call and form.