It is important to note that the money market vehicles you are citing are not money market accounts, but money market funds. There is one major difference between a the two. The money you place in a money market account is FDIC insured, while money you place in a money market fund is not (though with a good money market fund the risk of losing money is infinitesimal). So if you want absolute safety, you'd better look at CDs or money market accounts. Otherwise the Vanguard funds you cited are all good, my preference being Prime. Personally I would go with CDs in your situation and lock in a good rate for the next 2 years.
42 y/o, married, retirement portfolio = 43 x annual expenses