What action can husband take if 498 a is quashed?

he can cite the false 498a case filed by you over him to claim divorce on the grounds of cruelty

Once quashing is done then file Wirt Petition (Mandamus) (Article 226 and Article 21, 19, 14 & 15) against the STATE only for violating the basic constitutional rights for baised investigation/no investigation by the police and charged on such IPCs based on false and concocted stories  and pray for cost for damage occurred & order / direction to register FIR against the culprits. You may get minimum 10 lakhs as cost. Please also do the same in-person.

In addition to the above experts(I would like to know whether U R the wife or someone else prresenting the case.) This is a very sensitive and a dangerous section regarding harrasment part is concerned.Ifit works out for the wife then she is at the top of the world,if it back fires then she is haunted by the husband and his family.Hence the wife has to be very careful in filing this complaint,with valid evidences.

Can U please mention the reasons submitted by the husband for getting it quashedin HC?

Here are the answers to your questions:

1) what action can husband take ?

Ans: The husband can immediately file a divorce petition praying for divorce.

2) can the wife ask for alimony from husband after quashing?

Ans: Yes, the wife can claim maintenance from husband by filing petition u/s 125 Cr.P.C./24 of HMA.   
  
3)what consequences wife can face after quashing is done.

Ans: It depends on the mood of the husband. 
  
4) can the husband ask for compensation from wife, if 498 a is quashed ?

Ans: No. However, the husband can file defamation suit against the wife and claim for damages for loss of reputation which might /might not work.    

my brother n my whole family have been trapped into this case..

is the wife eligible to get alimony even after 498 a is quashed?

you can file divoce suit against wife.

you can file case against wife under 182 IPC 

It is the wife asking what will happen.

Unless some body has enough time than only new cases will crop us otherwise every one will try to move on in life .