she shits on melees hard until you get armor. she's guaranteed to get her unburrow + Qx3 combo off if you go into melee range so it's better to just avoid her unless she unburrows until you get a decent chunk of armor.
i play riven so it's a really annoying lane for me due to my low sustain. you can't deny her farm because she just takes it with her burrowed skillshot. if you go in for small trades she just heals up with her passive regeneration. if you all in she unburrows and wins the trade before tunnelling away.
i really hate rushing armor on riven but in this matchup i've been getting an early cloth armor, preferably after brutalizer, to reduce a lot of her damage from the guaranteed trade. i haven't experimented with a cloth5 start and saving up 1337 for a brutalizer on recall yet, but that may work better. it feels like i run out of potions quickly since she can just sit in the minion wave and unburrow -> combo me when i go in to CS. if you get brutalizer + cloth without dying you just straight up win though, so at least there's that :]