Savings account options

[Jayme Carlson]

New investor here. I own one duplex and I'm living in one of the units. My goal is to buy at least one 2-4 unit property every year for the foreseeable future. My question is about financing. When I was getting the loan on the first one, the underwriter was wanting to see 6 months worth of reserves ($3000) in savings or some other form of liquid assets. Now that I'm starting to look for my second property, I have been informed that they will want to see 6 months worth of reserves for each property I own, on top of the one I'm applying for a loan for. I have a 401K, but it doesn't have any options for hardship withdraw. So I'm trying to figure out what my options are for a type of savings account that I can keep these reserves in. Something that has a decent return, so my money isn't just sitting there. But it also needs to be decently liquid. 

I am a bit naive as to all the investment account options out there. Should I be looking at some sort of mutual fund? Or an IRA? I have a few hundred dollars in a lending club account, should I add to it and use that? Is that liquid enough?