200 max buy in question

[ClaudCunningham]

200 dollar max buy in NL table (at bellagio)

2/5 blinds ....just got moved from a "feeder" table to their 2 main NL
tables with 280 bucks ...moved to main table with at least 6 stacks over
700

saw about 6 hands ...played 2 from late position (KQ) and (AJ) folded when
no help and huge bets start coming out

player to my left has about 350 and is getting annoyed with no playable
hands...(he was "whining a bit")

here's the hand he got to play with me...

7 limpers ....

i've got pocket 4's and i call from small blind

flop comes Qc 7c 4d

i bet out for 20

he comes over the top for 50.... (i put him on a flush draw or 2 pair)

my question is what bet would you throw back at this point to him????

thanks in advance......