Is it permissible to ask for help from those in blessed graves?

Dear Mufti Sahib, Ashlamualaiykum, I would like to know it is allow to ask our requirement to peer/wali/auliya who is in blessed grave, are they able to help us, if yes please dalil, if they are not able to help us why maulana qasim nanotvi saheb came two time from his grave and helped to deobandi people, one time maulana nanotvi saheb came to darul uloom deoband to help maulana rafiuddin saheb who has dispute with other ulemas of deoband and second time he was came in punjab (india) when deobandi alim was doing munazara (debating with barelvi alim) then maulana nanotiv saheb came with his body (not only rooh), kindly note that above two incidence is noted from Arwahe Salasha it is composed by well-known deobandi school, as barelvi accused on deobandi. Please clarify, this is not for insult of anyone, i am barelvi but I respect some of deobandi idea which is really good and according to sunnah and quran. Please sir don’t take it otherwise. Thanks