Liquid savings, how much?

My husband and I are 55, together for ten years. In the early years I begged to establish some savings and my husband (the spender) did not want to. He does have alot in his 401k. We have some debt but its from home renovations and we pay it off pretty quickly.

Recently he has started to see the value in savings and we had $10k saved up. He wanted to put 5 K into T-bills (better interest), than wanted to put 3k into Vanguard. We save $300 per month in regular savings, $300 per month in T-bills. He wants me to take the $300 for savings and put it into Vanguard since our savings is $2500 – liquid savings.

I get that liquid savings does not get as high of interest, but its for emergencies that might arise and it gives me anxiety to not have it.

So my question – what sort of liquid savings do you have and how much?