April 8, 1981

Tucked away in the heart of this New Jersey city, the Prudential Insurance Company of America is somewhat removed from the competitive fervor of Wall Street. But geography has not daunted the Pru's expansion into financial services, and its desire to add new lines of business. Not content to be both the largest life insurer and the largest private money manager in the United States, the mutual company recently made a $385 million bid for the Bache Group, the fifth-largest retail brokerage firm in the country. For Prudential thinks Bache has the potential to be No.1. ''Acquiring Bache will be a very significant step in our strategic plan to offer a broad range of financial services,'' said Robert A. Beck, Prudential's 55-year-old, cigar-chomping chairman. ''From our standpoint, it is an extension of a program we have already been on.''

The Reagan Administration publicly took the position today that despite all the worrisome signs, a Soviet invasion of Poland is neither imminent or inevitable. Others with long experience of Moscow's policies expressed serious caution about the outlook. They see the Kremlin either aiming to install tougher leaders in Poland or pressing the present leaders into a crackdown against the independent labor union, Solidarity, and inclined to resort to force if the Polish Communist Party does not take tougher action. With Leonid I. Brezhnev now visiting Prague, several former high American officials are drawing parallels between the intensive Soviet pressure on Poland and the moves that Moscow made in 1968 as a prelude to the invasion of Czechoslovakia by Warsaw Pact powers. Then as now, there were menacing military maneuvers, high-level meetings and propaganda charges about ''counterrevolution'' and Western subversion.

SHOP for specials and redeem coupons: These are obvious methods of stretching grocery dollars. By applying a number of other commonsense strategies, the budget-conscious food shopper - and who isn't? - can further alleviate the pain at the supermarket checkout counter. It is hardly consoling to know that the percentage of the consumer dollar spent on food in the United States, less than 20 percent, is low compared with that in other countries. (For example, the average Latin American spends 64 percent of his income on food and does not eat as well.) But there is every indication that our food prices will continue to escalate while the budget is squeezed by rocketing costs of housing, energy and transportation. The little purple numbers and the unit prices are not going to shrink, so careful planning is essential. People who manage their grocery money well usually take the time to project their needs for the week, outlining menus and writing lists. Even if you live in Manhattan and market frequently, it's a good idea to plan from week to week.

ONCE most of us have filed our tax returns, we feel too poor and depressed to entertain. But take heart. If you've invited friends for dinner it is possible, even these days, to serve a delicious dinner to eight guests for less than $25. Mexican and Indian food is the inspiration for the two menus given on page C6. The food may be exotic but it is not expensive. The two cuisines rely heavily on spices and aromatics, chili peppers, coriander and mint leaves.

The New York City Taxi and Limousine Commission is expected today to impose a 50-cent surcharge for night and Sunday taxi rides in what it says is an effort to get more cabs on the city's streets. If approved as expected, the extra charge would go into effect by the end this month for an eight-month trial period. As proposed, the charge would be added to rides taken from 8 P.M. to 6 A.M. daily and all day Sunday. The surcharge is designed to encourage more taxi drivers to work during hours in which, according to commission studies, there is a scarcity of cabs.