$150 for 2 days is more than reasaonable. I would offer him that and nothing more.
$75 a day for $25 per meal. reason I came up with $150. avg. per diem for Bay Area.
Any email correspondence, phone calls- dates, what was discussed etc..
Here are some resources you can use
which says "So, what is the average cost of groceries per person, according to 1Food Spendng by American Householdsâ€¦1? $1,347.oo, or $112.25 per month."