My wife is about 2.5 months pregnant. Since last 5-10 days , she mostly starts vomitting whenever used to take foods...but this problem not happens while taking fruits and other things..

It's normal during pregnancy. Please read this article
Vomiting During Pregnancy - A Definite Sign Of Pregnancy

It is normal.. ask hr to have fruits and more water. Keep hydrated with nimbu pani.
Nauseous? 8 Ways To Prevent Morning Sickness
If vomit occurs too much, talk to doc for a med.