buy the bare minimum of food to prepare for a possible quarantine
buy some essential food to last for a while just in case you need to be in quarantine
「隔離に備えて必要最低限の食料を買う」は下のように言えます。
ーbuy the bare minimum of food to prepare for a possible quarantine
bare minimum of food で「必要最低限の食料」
prepare for a possible quarantine で「起こりうる隔離に備える」
ーbuy some essential food to last for a while just in case you need to be in quarantine
essential food で「必要最低限の食料」とも言えます。
last「(物がある期間の間)間に合う」
just in case「万が一のため・もしもの時」
in quarantine 「隔離中で」
例:
You better buy some essential food to last for a while just in case you need to be in quarantine/isolation.
「万が一隔離する必要がある時のため、しばらくの間もつ必要最低限の食料を買ったほうが良いよ。」
ご参考まで!